API for clojure.core - Clojure v1.6 (legacy)

Full namespace name: clojure.core

Overview

Fundamental library of the Clojure language

Types

ArrayChunk

type

Fields: [am arr off end]
Protocols:
Interfaces: clojure.lang.IChunk, clojure.lang.Indexed

Vec

type

Fields: [am cnt shift root tail _meta]
Protocols:
Interfaces: clojure.core.IVecImpl, clojure.lang.Associative, clojure.lang.Counted, clojure.lang.IFn, clojure.lang.IHashEq, clojure.lang.ILookup, clojure.lang.IMeta, clojure.lang.IObj, clojure.lang.IPersistentCollection, clojure.lang.IPersistentStack, clojure.lang.IPersistentVector, clojure.lang.Indexed, clojure.lang.Reversible, clojure.lang.Seqable, clojure.lang.Sequential, java.lang.Comparable, java.lang.Iterable, java.util.Collection, java.util.List

VecNode

type

Fields: [edit arr]
Protocols:
Interfaces:

VecSeq

type

Fields: [am vec anode i offset]
Protocols: clojure.core.protocols/InternalReduce
Interfaces: clojure.lang.IChunkedSeq, clojure.lang.ISeq, clojure.lang.Seqable

Public Variables and Functions

&

special syntax

Syntax for use with fn.

Please see https://clojure.org/reference/special_forms#fn

Added in Clojure version 1.0

*

function

Usage: (*)
       (* x)
       (* x y)
       (* x y & more)

Returns the product of nums. (*) returns 1. Does not auto-promote
longs, will throw on overflow. See also: *'

Added in Clojure version 1.2
Source

*'

function

Usage: (*')
       (*' x)
       (*' x y)
       (*' x y & more)

Returns the product of nums. (*) returns 1. Supports arbitrary precision.
See also: *

Added in Clojure version 1.0
Source

*1

dynamic var

bound in a repl thread to the most recent value printed

Added in Clojure version 1.0
Source

*2

dynamic var

bound in a repl thread to the second most recent value printed

Added in Clojure version 1.0
Source

*3

dynamic var

bound in a repl thread to the third most recent value printed

Added in Clojure version 1.0
Source

agent

var

The agent currently running an action on this thread, else nil

Added in Clojure version 1.0

clojure-version

dynamic var

The version info for Clojure core, as a map containing :major :minor 
:incremental and :qualifier keys. Feature releases may increment 
:minor and/or :major, bugfix releases will increment :incremental. 
Possible values of :qualifier include "GA", "SNAPSHOT", "RC-x" "BETA-x"

Added in Clojure version 1.0
Source

command-line-args

var

A sequence of the supplied command line arguments, or nil if
none were supplied

Added in Clojure version 1.0

compile-files

var

Set to true when compiling files, false otherwise.

Added in Clojure version 1.0

compile-path

var

Specifies the directory where 'compile' will write out .class
files. This directory must be in the classpath for 'compile' to
work.

Defaults to "classes"

Added in Clojure version 1.0

compiler-options

var

A map of keys to options.
Note, when binding dynamically make sure to merge with previous value.
Supported options:
:elide-meta - a collection of metadata keys to elide during compilation.
:disable-locals-clearing - set to true to disable clearing, useful for using a debugger
Alpha, subject to change.

Added in Clojure version 1.4

data-readers

dynamic var

Map from reader tag symbols to data reader Vars.

When Clojure starts, it searches for files named 'data_readers.clj'
at the root of the classpath. Each such file must contain a literal
map of symbols, like this:

    {foo/bar my.project.foo/bar
     foo/baz my.project/baz}

The first symbol in each pair is a tag that will be recognized by
the Clojure reader. The second symbol in the pair is the
fully-qualified name of a Var which will be invoked by the reader to
parse the form following the tag. For example, given the
data_readers.clj file above, the Clojure reader would parse this
form:

    #foo/bar [1 2 3]

by invoking the Var #'my.project.foo/bar on the vector [1 2 3]. The
data reader function is invoked on the form AFTER it has been read
as a normal Clojure data structure by the reader.

Reader tags without namespace qualifiers are reserved for
Clojure. Default reader tags are defined in
clojure.core/default-data-readers but may be overridden in
data_readers.clj or by rebinding this Var.

Added in Clojure version 1.4
Source

default-data-reader-fn

dynamic var

When no data reader is found for a tag and *default-data-reader-fn*
is non-nil, it will be called with two arguments,
the tag and the value.  If *default-data-reader-fn* is nil (the
default), an exception will be thrown for the unknown tag.

Added in Clojure version 1.5
Source

*e

dynamic var

bound in a repl thread to the most recent exception caught by the repl

Added in Clojure version 1.0
Source

err

var

A java.io.Writer object representing standard error for print operations.

Defaults to System/err, wrapped in a PrintWriter

Added in Clojure version 1.0

file

var

The path of the file being evaluated, as a String.

When there is no file, e.g. in the REPL, the value is not defined.

Added in Clojure version 1.0

flush-on-newline

var

When set to true, output will be flushed whenever a newline is printed.

Defaults to true.

Added in Clojure version 1.0

in

var

A java.io.Reader object representing standard input for read operations.

Defaults to System/in, wrapped in a LineNumberingPushbackReader

Added in Clojure version 1.0

ns

var

A clojure.lang.Namespace object representing the current namespace.

Added in Clojure version 1.0

out

var

A java.io.Writer object representing standard output for print operations.

Defaults to System/out, wrapped in an OutputStreamWriter

Added in Clojure version 1.0

print-dup

var

When set to logical true, objects will be printed in a way that preserves
their type when read in later.

Defaults to false.

Added in Clojure version 1.0

print-length

dynamic var

*print-length* controls how many items of each collection the
printer will print. If it is bound to logical false, there is no
limit. Otherwise, it must be bound to an integer indicating the maximum
number of items of each collection to print. If a collection contains
more items, the printer will print items up to the limit followed by
'...' to represent the remaining items. The root binding is nil
indicating no limit.

Added in Clojure version 1.0
Source

print-level

dynamic var

*print-level* controls how many levels deep the printer will
print nested objects. If it is bound to logical false, there is no
limit. Otherwise, it must be bound to an integer indicating the maximum
level to print. Each argument to print is at level 0; if an argument is a
collection, its items are at level 1; and so on. If an object is a
collection and is at a level greater than or equal to the value bound to
*print-level*, the printer prints '#' to represent it. The root binding
is nil indicating no limit.

Added in Clojure version 1.0
Source

print-meta

var

If set to logical true, when printing an object, its metadata will also
be printed in a form that can be read back by the reader.

Defaults to false.

Added in Clojure version 1.0

print-readably

var

When set to logical false, strings and characters will be printed with
non-alphanumeric characters converted to the appropriate escape sequences.

Defaults to true

Added in Clojure version 1.0

read-eval

var

Defaults to true (or value specified by system property, see below)
***This setting implies that the full power of the reader is in play,
including syntax that can cause code to execute. It should never be
used with untrusted sources. See also: clojure.edn/read.***

When set to logical false in the thread-local binding,
the eval reader (#=) and record/type literal syntax are disabled in read/load.
Example (will fail): (binding [*read-eval* false] (read-string "#=(* 2 21)"))

The default binding can be controlled by the system property
'clojure.read.eval' System properties can be set on the command line
like this:

java -Dclojure.read.eval=false ...

The system property can also be set to 'unknown' via
-Dclojure.read.eval=unknown, in which case the default binding
is :unknown and all reads will fail in contexts where *read-eval*
has not been explicitly bound to either true or false. This setting
can be a useful diagnostic tool to ensure that all of your reads
occur in considered contexts. You can also accomplish this in a
particular scope by binding *read-eval* to :unknown

Added in Clojure version 1.0

unchecked-math

var

While bound to true, compilations of +, -, *, inc, dec and the
coercions will be done without overflow checks. Default: false.

Added in Clojure version 1.3

warn-on-reflection

var

When set to true, the compiler will emit warnings when reflection is
needed to resolve Java method calls or field accesses.

Defaults to false.

Added in Clojure version 1.0

+

function

Usage: (+)
       (+ x)
       (+ x y)
       (+ x y & more)

Returns the sum of nums. (+) returns 0. Does not auto-promote
longs, will throw on overflow. See also: +'

Added in Clojure version 1.2
Source

+'

function

Usage: (+')
       (+' x)
       (+' x y)
       (+' x y & more)

Returns the sum of nums. (+) returns 0. Supports arbitrary precision.
See also: +

Added in Clojure version 1.0
Source

-

function

Usage: (- x)
       (- x y)
       (- x y & more)

If no ys are supplied, returns the negation of x, else subtracts
the ys from x and returns the result. Does not auto-promote
longs, will throw on overflow. See also: -'

Added in Clojure version 1.2
Source

-'

function

Usage: (-' x)
       (-' x y)
       (-' x y & more)

If no ys are supplied, returns the negation of x, else subtracts
the ys from x and returns the result. Supports arbitrary precision.
See also: -

Added in Clojure version 1.0
Source

->

macro

Usage: (-> x & forms)

Threads the expr through the forms. Inserts x as the
second item in the first form, making a list of it if it is not a
list already. If there are more forms, inserts the first form as the
second item in second form, etc.

Added in Clojure version 1.0
Source

->>

macro

Usage: (->> x & forms)

Threads the expr through the forms. Inserts x as the
last item in the first form, making a list of it if it is not a
list already. If there are more forms, inserts the first form as the
last item in second form, etc.

Added in Clojure version 1.1
Source

->ArrayChunk

function

Usage: (->ArrayChunk am arr off end)

Positional factory function for class clojure.core.ArrayChunk.

Source

->Vec

function

Usage: (->Vec am cnt shift root tail _meta)

Positional factory function for class clojure.core.Vec.

Source

->VecNode

function

Usage: (->VecNode edit arr)

Positional factory function for class clojure.core.VecNode.

Source

->VecSeq

function

Usage: (->VecSeq am vec anode i offset)

Positional factory function for class clojure.core.VecSeq.

Source

.

special form

Usage: (.instanceMember instance args*)
       (.instanceMember Classname args*)
       (Classname/staticMethod args*)
       Classname/staticField

The instance member form works for both fields and methods.
They all expand into calls to the dot operator at macroexpansion time.

Please see https://clojure.org/java_interop#dot

Added in Clojure version 1.0

..

macro

Usage: (.. x form)
       (.. x form & more)

form => fieldName-symbol or (instanceMethodName-symbol args*)

Expands into a member access (.) of the first member on the first
argument, followed by the next member on the result, etc. For
instance:

(.. System (getProperties) (get "os.name"))

expands to:

(. (. System (getProperties)) (get "os.name"))

but is easier to write, read, and understand.

Added in Clojure version 1.0
Source

/

function

Usage: (/ x)
       (/ x y)
       (/ x y & more)

If no denominators are supplied, returns 1/numerator,
else returns numerator divided by all of the denominators.

Added in Clojure version 1.0
Source

<

function

Usage: (< x)
       (< x y)
       (< x y & more)

Returns non-nil if nums are in monotonically increasing order,
otherwise false.

Added in Clojure version 1.0
Source

<=

function

Usage: (<= x)
       (<= x y)
       (<= x y & more)

Returns non-nil if nums are in monotonically non-decreasing order,
otherwise false.

Added in Clojure version 1.0
Source

=

function

Usage: (= x)
       (= x y)
       (= x y & more)

Equality. Returns true if x equals y, false if not. Same as
Java x.equals(y) except it also works for nil, and compares
numbers and collections in a type-independent manner.  Clojure's immutable data
structures define equals() (and thus =) as a value, not an identity,
comparison.

Added in Clojure version 1.0
Source

==

function

Usage: (== x)
       (== x y)
       (== x y & more)

Returns non-nil if nums all have the equivalent
value (type-independent), otherwise false

Added in Clojure version 1.0
Source

>

function

Usage: (> x)
       (> x y)
       (> x y & more)

Returns non-nil if nums are in monotonically decreasing order,
otherwise false.

Added in Clojure version 1.0
Source

>=

function

Usage: (>= x)
       (>= x y)
       (>= x y & more)

Returns non-nil if nums are in monotonically non-increasing order,
otherwise false.

Added in Clojure version 1.0
Source

accessor

function

Usage: (accessor s key)

Returns a fn that, given an instance of a structmap with the basis,
returns the value at the key.  The key must be in the basis. The
returned function should be (slightly) more efficient than using
get, but such use of accessors should be limited to known
performance-critical areas.

Added in Clojure version 1.0
Source

aclone

function

Usage: (aclone array)

Returns a clone of the Java array. Works on arrays of known
types.

Added in Clojure version 1.0
Source

add-classpath

function

Usage: (add-classpath url)

DEPRECATED 

Adds the url (String or URL object) to the classpath per
URLClassLoader.addURL

Added in Clojure version 1.0
Deprecated since Clojure version 1.1
Source

add-watch

function

Usage: (add-watch reference key fn)

Adds a watch function to an agent/atom/var/ref reference. The watch
fn must be a fn of 4 args: a key, the reference, its old-state, its
new-state. Whenever the reference's state might have been changed,
any registered watches will have their functions called. The watch fn
will be called synchronously, on the agent's thread if an agent,
before any pending sends if agent or ref. Note that an atom's or
ref's state may have changed again prior to the fn call, so use
old/new-state rather than derefing the reference. Note also that watch
fns may be called from multiple threads simultaneously. Var watchers
are triggered only by root binding changes, not thread-local
set!s. Keys must be unique per reference, and can be used to remove
the watch with remove-watch, but are otherwise considered opaque by
the watch mechanism.

Added in Clojure version 1.0
Source

agent

function

Usage: (agent state & options)

Creates and returns an agent with an initial value of state and
zero or more options (in any order):

:meta metadata-map

:validator validate-fn

:error-handler handler-fn

:error-mode mode-keyword

If metadata-map is supplied, it will become the metadata on the
agent. validate-fn must be nil or a side-effect-free fn of one
argument, which will be passed the intended new state on any state
change. If the new state is unacceptable, the validate-fn should
return false or throw an exception.  handler-fn is called if an
action throws an exception or if validate-fn rejects a new state --
see set-error-handler! for details.  The mode-keyword may be either
:continue (the default if an error-handler is given) or :fail (the
default if no error-handler is given) -- see set-error-mode! for
details.

Added in Clojure version 1.0
Source

agent-error

function

Usage: (agent-error a)

Returns the exception thrown during an asynchronous action of the
agent if the agent is failed.  Returns nil if the agent is not
failed.

Added in Clojure version 1.2
Source

agent-errors

function

Usage: (agent-errors a)

DEPRECATED: Use 'agent-error' instead.
Returns a sequence of the exceptions thrown during asynchronous
actions of the agent.

Added in Clojure version 1.0
Deprecated since Clojure version 1.2
Source

aget

function

Usage: (aget array idx)
       (aget array idx & idxs)

Returns the value at the index/indices. Works on Java arrays of all
types.

Added in Clojure version 1.0
Source

alength

function

Usage: (alength array)

Returns the length of the Java array. Works on arrays of all
types.

Added in Clojure version 1.0
Source

alias

function

Usage: (alias alias namespace-sym)

Add an alias in the current namespace to another
namespace. Arguments are two symbols: the alias to be used, and
the symbolic name of the target namespace. Use :as in the ns macro in preference
to calling this directly.

Added in Clojure version 1.0
Source

all-ns

function

Usage: (all-ns)

Returns a sequence of all namespaces.

Added in Clojure version 1.0
Source

alter

function

Usage: (alter ref fun & args)

Must be called in a transaction. Sets the in-transaction-value of
ref to:

(apply fun in-transaction-value-of-ref args)

and returns the in-transaction-value of ref.

Added in Clojure version 1.0
Source

alter-meta!

function

Usage: (alter-meta! iref f & args)

Atomically sets the metadata for a namespace/var/ref/agent/atom to be:

(apply f its-current-meta args)

f must be free of side-effects

Added in Clojure version 1.0
Source

alter-var-root

function

Usage: (alter-var-root v f & args)

Atomically alters the root binding of var v by applying f to its
current value plus any args

Added in Clojure version 1.0
Source

amap

macro

Usage: (amap a idx ret expr)

Maps an expression across an array a, using an index named idx, and
return value named ret, initialized to a clone of a, then setting 
each element of ret to the evaluation of expr, returning the new 
array ret.

Added in Clojure version 1.0
Source

ancestors

function

Usage: (ancestors tag)
       (ancestors h tag)

Returns the immediate and indirect parents of tag, either via a Java type
inheritance relationship or a relationship established via derive. h
must be a hierarchy obtained from make-hierarchy, if not supplied
defaults to the global hierarchy

Added in Clojure version 1.0
Source

and

macro

Usage: (and)
       (and x)
       (and x & next)

Evaluates exprs one at a time, from left to right. If a form
returns logical false (nil or false), and returns that value and
doesn't evaluate any of the other expressions, otherwise it returns
the value of the last expr. (and) returns true.

Added in Clojure version 1.0
Source

apply

function

Usage: (apply f args)
       (apply f x args)
       (apply f x y args)
       (apply f x y z args)
       (apply f a b c d & args)

Applies fn f to the argument list formed by prepending intervening arguments to args.

Added in Clojure version 1.0
Source

areduce

macro

Usage: (areduce a idx ret init expr)

Reduces an expression across an array a, using an index named idx,
and return value named ret, initialized to init, setting ret to the 
evaluation of expr at each step, returning ret.

Added in Clojure version 1.0
Source

array-map

function

Usage: (array-map)
       (array-map & keyvals)

Constructs an array-map. If any keys are equal, they are handled as
if by repeated uses of assoc.

Added in Clojure version 1.0
Source

as->

macro

Usage: (as-> expr name & forms)

Binds name to expr, evaluates the first form in the lexical context
of that binding, then binds name to that result, repeating for each
successive form, returning the result of the last form.

Added in Clojure version 1.5
Source

aset

function

Usage: (aset array idx val)
       (aset array idx idx2 & idxv)

Sets the value at the index/indices. Works on Java arrays of
reference types. Returns val.

Added in Clojure version 1.0
Source

aset-boolean

function

Usage: (aset-boolean array idx val)
       (aset-boolean array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of boolean. Returns val.

Added in Clojure version 1.0
Source

aset-byte

function

Usage: (aset-byte array idx val)
       (aset-byte array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of byte. Returns val.

Added in Clojure version 1.0
Source

aset-char

function

Usage: (aset-char array idx val)
       (aset-char array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of char. Returns val.

Added in Clojure version 1.0
Source

aset-double

function

Usage: (aset-double array idx val)
       (aset-double array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of double. Returns val.

Added in Clojure version 1.0
Source

aset-float

function

Usage: (aset-float array idx val)
       (aset-float array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of float. Returns val.

Added in Clojure version 1.0
Source

aset-int

function

Usage: (aset-int array idx val)
       (aset-int array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of int. Returns val.

Added in Clojure version 1.0
Source

aset-long

function

Usage: (aset-long array idx val)
       (aset-long array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of long. Returns val.

Added in Clojure version 1.0
Source

aset-short

function

Usage: (aset-short array idx val)
       (aset-short array idx idx2 & idxv)

Sets the value at the index/indices. Works on arrays of short. Returns val.

Added in Clojure version 1.0
Source

assert

macro

Usage: (assert x)
       (assert x message)

Evaluates expr and throws an exception if it does not evaluate to
logical true.

Added in Clojure version 1.0
Source

assoc

function

Usage: (assoc map key val)
       (assoc map key val & kvs)

assoc[iate]. When applied to a map, returns a new map of the
same (hashed/sorted) type, that contains the mapping of key(s) to
val(s). When applied to a vector, returns a new vector that
contains val at index. Note - index must be <= (count vector).

Added in Clojure version 1.0
Source

assoc!

function

Usage: (assoc! coll key val)
       (assoc! coll key val & kvs)

When applied to a transient map, adds mapping of key(s) to
val(s). When applied to a transient vector, sets the val at index.
Note - index must be <= (count vector). Returns coll.

Added in Clojure version 1.1
Source

assoc-in

function

Usage: (assoc-in m [k & ks] v)

Associates a value in a nested associative structure, where ks is a
sequence of keys and v is the new value and returns a new nested structure.
If any levels do not exist, hash-maps will be created.

Added in Clojure version 1.0
Source

associative?

function

Usage: (associative? coll)

Returns true if coll implements Associative

Added in Clojure version 1.0
Source

atom

function

Usage: (atom x)
       (atom x & options)

Creates and returns an Atom with an initial value of x and zero or
more options (in any order):

:meta metadata-map

:validator validate-fn

If metadata-map is supplied, it will become the metadata on the
atom. validate-fn must be nil or a side-effect-free fn of one
argument, which will be passed the intended new state on any state
change. If the new state is unacceptable, the validate-fn should
return false or throw an exception.

Added in Clojure version 1.0
Source

await

function

Usage: (await & agents)

Blocks the current thread (indefinitely!) until all actions
dispatched thus far, from this thread or agent, to the agent(s) have
occurred.  Will block on failed agents.  Will never return if
a failed agent is restarted with :clear-actions true.

Added in Clojure version 1.0
Source

await-for

function

Usage: (await-for timeout-ms & agents)

Blocks the current thread until all actions dispatched thus
far (from this thread or agent) to the agents have occurred, or the
timeout (in milliseconds) has elapsed. Returns logical false if
returning due to timeout, logical true otherwise.

Added in Clojure version 1.0
Source

bases

function

Usage: (bases c)

Returns the immediate superclass and direct interfaces of c, if any

Added in Clojure version 1.0
Source

bean

function

Usage: (bean x)

Takes a Java object and returns a read-only implementation of the
map abstraction based upon its JavaBean properties.

Added in Clojure version 1.0
Source

bigdec

function

Usage: (bigdec x)

Coerce to BigDecimal

Added in Clojure version 1.0
Source

bigint

function

Usage: (bigint x)

Coerce to BigInt

Added in Clojure version 1.3
Source

biginteger

function

Usage: (biginteger x)

Coerce to BigInteger

Added in Clojure version 1.0
Source

binding

macro

Usage: (binding bindings & body)

binding => var-symbol init-expr

Creates new bindings for the (already-existing) vars, with the
supplied initial values, executes the exprs in an implicit do, then
re-establishes the bindings that existed before.  The new bindings
are made in parallel (unlike let); all init-exprs are evaluated
before the vars are bound to their new values.

Added in Clojure version 1.0
Source

bit-and

function

Usage: (bit-and x y)
       (bit-and x y & more)

Bitwise and

Added in Clojure version 1.0
Source

bit-and-not

function

Usage: (bit-and-not x y)
       (bit-and-not x y & more)

Bitwise and with complement

Added in Clojure version 1.0
Source

bit-clear

function

Usage: (bit-clear x n)

Clear bit at index n

Added in Clojure version 1.0
Source

bit-flip

function

Usage: (bit-flip x n)

Flip bit at index n

Added in Clojure version 1.0
Source

bit-not

function

Usage: (bit-not x)

Bitwise complement

Added in Clojure version 1.0
Source

bit-or

function

Usage: (bit-or x y)
       (bit-or x y & more)

Bitwise or

Added in Clojure version 1.0
Source

bit-set

function

Usage: (bit-set x n)

Set bit at index n

Added in Clojure version 1.0
Source

bit-shift-left

function

Usage: (bit-shift-left x n)

Bitwise shift left

Added in Clojure version 1.0
Source

bit-shift-right

function

Usage: (bit-shift-right x n)

Bitwise shift right

Added in Clojure version 1.0
Source

bit-test

function

Usage: (bit-test x n)

Test bit at index n

Added in Clojure version 1.0
Source

bit-xor

function

Usage: (bit-xor x y)
       (bit-xor x y & more)

Bitwise exclusive or

Added in Clojure version 1.0
Source

boolean

function

Usage: (boolean x)

Coerce to boolean

Added in Clojure version 1.0
Source

boolean-array

function

Usage: (boolean-array size-or-seq)
       (boolean-array size init-val-or-seq)

Creates an array of booleans

Added in Clojure version 1.1
Source

booleans

function

Usage: (booleans xs)

Casts to boolean[]

Added in Clojure version 1.1
Source

bound-fn

macro

Usage: (bound-fn & fntail)

Returns a function defined by the given fntail, which will install the
same bindings in effect as in the thread at the time bound-fn was called.
This may be used to define a helper function which runs on a different
thread, but needs the same bindings in place.

Added in Clojure version 1.1
Source

bound-fn*

function

Usage: (bound-fn* f)

Returns a function, which will install the same bindings in effect as in
the thread at the time bound-fn* was called and then call f with any given
arguments. This may be used to define a helper function which runs on a
different thread, but needs the same bindings in place.

Added in Clojure version 1.1
Source

bound?

function

Usage: (bound? & vars)

Returns true if all of the vars provided as arguments have any bound value, root or thread-local.
Implies that deref'ing the provided vars will succeed. Returns true if no vars are provided.

Added in Clojure version 1.2
Source

butlast

function

Usage: (butlast coll)

Return a seq of all but the last item in coll, in linear time

Added in Clojure version 1.0
Source

byte

function

Usage: (byte x)

Coerce to byte

Added in Clojure version 1.0
Source

byte-array

function

Usage: (byte-array size-or-seq)
       (byte-array size init-val-or-seq)

Creates an array of bytes

Added in Clojure version 1.1
Source

bytes

function

Usage: (bytes xs)

Casts to bytes[]

Added in Clojure version 1.1
Source

case

macro

Usage: (case e & clauses)

Takes an expression, and a set of clauses.

Each clause can take the form of either:

test-constant result-expr

(test-constant1 ... test-constantN)  result-expr

The test-constants are not evaluated. They must be compile-time
literals, and need not be quoted.  If the expression is equal to a
test-constant, the corresponding result-expr is returned. A single
default expression can follow the clauses, and its value will be
returned if no clause matches. If no default expression is provided
and no clause matches, an IllegalArgumentException is thrown.

Unlike cond and condp, case does a constant-time dispatch, the
clauses are not considered sequentially.  All manner of constant
expressions are acceptable in case, including numbers, strings,
symbols, keywords, and (Clojure) composites thereof. Note that since
lists are used to group multiple constants that map to the same
expression, a vector can be used to match a list if needed. The
test-constants need not be all of the same type.

Added in Clojure version 1.2
Source

cast

function

Usage: (cast c x)

Throws a ClassCastException if x is not a c, else returns x.

Added in Clojure version 1.0
Source

catch

special syntax

Syntax for use with try.

Please see https://clojure.org/reference/special_forms#try

Added in Clojure version 1.0

char

function

Usage: (char x)

Coerce to char

Added in Clojure version 1.1
Source

char-array

function

Usage: (char-array size-or-seq)
       (char-array size init-val-or-seq)

Creates an array of chars

Added in Clojure version 1.1
Source

char-escape-string

var

Returns escape string for char or nil if none

Added in Clojure version 1.0
Source

char-name-string

var

Returns name string for char or nil if none

Added in Clojure version 1.0
Source

char?

function

Usage: (char? x)

Return true if x is a Character

Added in Clojure version 1.0
Source

chars

function

Usage: (chars xs)

Casts to chars[]

Added in Clojure version 1.1
Source

class

function

Usage: (class x)

Returns the Class of x

Added in Clojure version 1.0
Source

class?

function

Usage: (class? x)

Returns true if x is an instance of Class

Added in Clojure version 1.0
Source

clear-agent-errors

function

Usage: (clear-agent-errors a)

DEPRECATED: Use 'restart-agent' instead.
Clears any exceptions thrown during asynchronous actions of the
agent, allowing subsequent actions to occur.

Added in Clojure version 1.0
Deprecated since Clojure version 1.2
Source

clojure-version

function

Usage: (clojure-version)

Returns clojure version as a printable string.

Added in Clojure version 1.0
Source

coll?

function

Usage: (coll? x)

Returns true if x implements IPersistentCollection

Added in Clojure version 1.0
Source

comment

macro

Usage: (comment & body)

Ignores body, yields nil

Added in Clojure version 1.0
Source

commute

function

Usage: (commute ref fun & args)

Must be called in a transaction. Sets the in-transaction-value of
ref to:

(apply fun in-transaction-value-of-ref args)

and returns the in-transaction-value of ref.

At the commit point of the transaction, sets the value of ref to be:

(apply fun most-recently-committed-value-of-ref args)

Thus fun should be commutative, or, failing that, you must accept
last-one-in-wins behavior.  commute allows for more concurrency than
ref-set.

Added in Clojure version 1.0
Source

comp

function

Usage: (comp)
       (comp f)
       (comp f g)
       (comp f g h)
       (comp f1 f2 f3 & fs)

Takes a set of functions and returns a fn that is the composition
of those fns.  The returned fn takes a variable number of args,
applies the rightmost of fns to the args, the next
fn (right-to-left) to the result, etc.

Added in Clojure version 1.0
Source

comparator

function

Usage: (comparator pred)

Returns an implementation of java.util.Comparator based upon pred.

Added in Clojure version 1.0
Source

compare

function

Usage: (compare x y)

Comparator. Returns a negative number, zero, or a positive number
when x is logically 'less than', 'equal to', or 'greater than'
y. Same as Java x.compareTo(y) except it also works for nil, and
compares numbers and collections in a type-independent manner. x
must implement Comparable

Added in Clojure version 1.0
Source

compare-and-set!

function

Usage: (compare-and-set! atom oldval newval)

Atomically sets the value of atom to newval if and only if the
current value of the atom is identical to oldval. Returns true if
set happened, else false

Added in Clojure version 1.0
Source

compile

function

Usage: (compile lib)

Compiles the namespace named by the symbol lib into a set of
classfiles. The source for the lib must be in a proper
classpath-relative directory. The output files will go into the
directory specified by *compile-path*, and that directory too must
be in the classpath.

Added in Clojure version 1.0
Source

complement

function

Usage: (complement f)

Takes a fn f and returns a fn that takes the same arguments as f,
has the same effects, if any, and returns the opposite truth value.

Added in Clojure version 1.0
Source

concat

function

Usage: (concat)
       (concat x)
       (concat x y)
       (concat x y & zs)

Returns a lazy seq representing the concatenation of the elements in the supplied colls.

Added in Clojure version 1.0
Source

cond

macro

Usage: (cond & clauses)

Takes a set of test/expr pairs. It evaluates each test one at a
time.  If a test returns logical true, cond evaluates and returns
the value of the corresponding expr and doesn't evaluate any of the
other tests or exprs. (cond) returns nil.

Added in Clojure version 1.0
Source

cond->

macro

Usage: (cond-> expr & clauses)

Takes an expression and a set of test/form pairs. Threads expr (via ->)
through each form for which the corresponding test
expression is true. Note that, unlike cond branching, cond-> threading does
not short circuit after the first true test expression.

Added in Clojure version 1.5
Source

cond->>

macro

Usage: (cond->> expr & clauses)

Takes an expression and a set of test/form pairs. Threads expr (via ->>)
through each form for which the corresponding test expression
is true.  Note that, unlike cond branching, cond->> threading does not short circuit
after the first true test expression.

Added in Clojure version 1.5
Source

condp

macro

Usage: (condp pred expr & clauses)

Takes a binary predicate, an expression, and a set of clauses.
Each clause can take the form of either:

test-expr result-expr

test-expr :>> result-fn

Note :>> is an ordinary keyword.

For each clause, (pred test-expr expr) is evaluated. If it returns
logical true, the clause is a match. If a binary clause matches, the
result-expr is returned, if a ternary clause matches, its result-fn,
which must be a unary function, is called with the result of the
predicate as its argument, the result of that call being the return
value of condp. A single default expression can follow the clauses,
and its value will be returned if no clause matches. If no default
expression is provided and no clause matches, an
IllegalArgumentException is thrown.

Added in Clojure version 1.0
Source

conj

function

Usage: (conj coll x)
       (conj coll x & xs)

conj[oin]. Returns a new collection with the xs
'added'. (conj nil item) returns (item).  The 'addition' may
happen at different 'places' depending on the concrete type.

Added in Clojure version 1.0
Source

conj!

function

Usage: (conj! coll x)

Adds x to the transient collection, and return coll. The 'addition'
may happen at different 'places' depending on the concrete type.

Added in Clojure version 1.1
Source

cons

function

Usage: (cons x seq)

Returns a new seq where x is the first element and seq is
the rest.

Added in Clojure version 1.0
Source

constantly

function

Usage: (constantly x)

Returns a function that takes any number of arguments and returns x.

Added in Clojure version 1.0
Source

construct-proxy

function

Usage: (construct-proxy c & ctor-args)

Takes a proxy class and any arguments for its superclass ctor and
creates and returns an instance of the proxy.

Added in Clojure version 1.0
Source

contains?

function

Usage: (contains? coll key)

Returns true if key is present in the given collection, otherwise
returns false.  Note that for numerically indexed collections like
vectors and Java arrays, this tests if the numeric key is within the
range of indexes. 'contains?' operates constant or logarithmic time;
it will not perform a linear search for a value.  See also 'some'.

Added in Clojure version 1.0
Source

count

function

Usage: (count coll)

Returns the number of items in the collection. (count nil) returns
0.  Also works on strings, arrays, and Java Collections and Maps

Added in Clojure version 1.0
Source

counted?

function

Usage: (counted? coll)

Returns true if coll implements count in constant time

Added in Clojure version 1.0
Source

create-ns

function

Usage: (create-ns sym)

Create a new namespace named by the symbol if one doesn't already
exist, returns it or the already-existing namespace of the same
name.

Added in Clojure version 1.0
Source

create-struct

function

Usage: (create-struct & keys)

Returns a structure basis object.

Added in Clojure version 1.0
Source

cycle

function

Usage: (cycle coll)

Returns a lazy (infinite!) sequence of repetitions of the items in coll.

Added in Clojure version 1.0
Source

dec

function

Usage: (dec x)

Returns a number one less than num. Does not auto-promote
longs, will throw on overflow. See also: dec'

Added in Clojure version 1.2
Source

dec'

function

Usage: (dec' x)

Returns a number one less than num. Supports arbitrary precision.
See also: dec

Added in Clojure version 1.0
Source

decimal?

function

Usage: (decimal? n)

Returns true if n is a BigDecimal

Added in Clojure version 1.0
Source

declare

macro

Usage: (declare & names)

defs the supplied var names with no bindings, useful for making forward declarations.

Added in Clojure version 1.0
Source

def

special form

Usage: (def symbol doc-string? init?)

Creates and interns a global var with the name
of symbol in the current namespace (*ns*) or locates such a var if
it already exists.  If init is supplied, it is evaluated, and the
root binding of the var is set to the resulting value.  If init is
not supplied, the root binding of the var is unaffected.

Please see https://clojure.org/reference/special_forms#def

Added in Clojure version 1.0

default-data-readers

var

Default map of data reader functions provided by Clojure. May be
overridden by binding *data-readers*.

Added in Clojure version 1.4
Source

definline

macro

Usage: (definline name & decl)

Experimental - like defmacro, except defines a named function whose
body is the expansion, calls to which may be expanded inline as if
it were a macro. Cannot be used with variadic (&) args.

Added in Clojure version 1.0
Source

definterface

macro

Usage: (definterface name & sigs)

Creates a new Java interface with the given name and method sigs.
The method return types and parameter types may be specified with type hints,
defaulting to Object if omitted.

(definterface MyInterface
  (^int method1 [x])
  (^Bar method2 [^Baz b ^Quux q]))

Added in Clojure version 1.2
Source

defmacro

macro

Usage: (defmacro name doc-string? attr-map? [params*] body)
       (defmacro name doc-string? attr-map? ([params*] body) + attr-map?)

Like defn, but the resulting function name is declared as a
macro and will be used as a macro by the compiler when it is
called.

Added in Clojure version 1.0
Source

defmethod

macro

Usage: (defmethod multifn dispatch-val & fn-tail)

Creates and installs a new method of multimethod associated with dispatch-value.

Added in Clojure version 1.0
Source

defmulti

macro

Usage: (defmulti name docstring? attr-map? dispatch-fn & options)

Creates a new multimethod with the associated dispatch function.
The docstring and attribute-map are optional.

Options are key-value pairs and may be one of:

:default

The default dispatch value, defaults to :default

:hierarchy

The value used for hierarchical dispatch (e.g. ::square is-a ::shape)

Hierarchies are type-like relationships that do not depend upon type
inheritance. By default Clojure's multimethods dispatch off of a
global hierarchy map.  However, a hierarchy relationship can be
created with the derive function used to augment the root ancestor
created with make-hierarchy.

Multimethods expect the value of the hierarchy option to be supplied as
a reference type e.g. a var (i.e. via the Var-quote dispatch macro #'
or the var special form).

Added in Clojure version 1.0
Source

defn

macro

Usage: (defn name doc-string? attr-map? [params*] prepost-map? body)
       (defn name doc-string? attr-map? ([params*] prepost-map? body) + attr-map?)

Same as (def name (fn [params* ] exprs*)) or (def
name (fn ([params* ] exprs*)+)) with any doc-string or attrs added
to the var metadata. prepost-map defines a map with optional keys
:pre and :post that contain collections of pre or post conditions.

Added in Clojure version 1.0
Source

defn-

macro

Usage: (defn- name & decls)

same as defn, yielding non-public def

Added in Clojure version 1.0
Source

defonce

macro

Usage: (defonce name expr)

defs name to have the root value of the expr iff the named var has no root value,
else expr is unevaluated

Added in Clojure version 1.0
Source

defprotocol

macro

Usage: (defprotocol name & opts+sigs)

A protocol is a named set of named methods and their signatures:
(defprotocol AProtocolName

  ;optional doc string
  "A doc string for AProtocol abstraction"

;method signatures
  (bar [this a b] "bar docs")
  (baz [this a] [this a b] [this a b c] "baz docs"))

No implementations are provided. Docs can be specified for the
protocol overall and for each method. The above yields a set of
polymorphic functions and a protocol object. All are
namespace-qualified by the ns enclosing the definition The resulting
functions dispatch on the type of their first argument, which is
required and corresponds to the implicit target object ('this' in 
Java parlance). defprotocol is dynamic, has no special compile-time 
effect, and defines no new types or classes. Implementations of 
the protocol methods can be provided using extend.

defprotocol will automatically generate a corresponding interface,
with the same name as the protocol, i.e. given a protocol:
my.ns/Protocol, an interface: my.ns.Protocol. The interface will
have methods corresponding to the protocol functions, and the
protocol will automatically work with instances of the interface.

Note that you should not use this interface with deftype or
reify, as they support the protocol directly:

(defprotocol P 
  (foo [this]) 
  (bar-me [this] [this y]))

(deftype Foo [a b c] 
 P
  (foo [this] a)
  (bar-me [this] b)
  (bar-me [this y] (+ c y)))

(bar-me (Foo. 1 2 3) 42)
=> 45

(foo 
  (let [x 42]
    (reify P 
      (foo [this] 17)
      (bar-me [this] x)
      (bar-me [this y] x))))
=> 17

Added in Clojure version 1.2
Source

defrecord

macro

Usage: (defrecord name [& fields] & opts+specs)

(defrecord name [fields*]  options* specs*)

Currently there are no options.

Each spec consists of a protocol or interface name followed by zero
or more method bodies:

protocol-or-interface-or-Object
(methodName [args*] body)*

Dynamically generates compiled bytecode for class with the given
name, in a package with the same name as the current namespace, the
given fields, and, optionally, methods for protocols and/or
interfaces.

The class will have the (immutable) fields named by
fields, which can have type hints. Protocols/interfaces and methods
are optional. The only methods that can be supplied are those
declared in the protocols/interfaces.  Note that method bodies are
not closures, the local environment includes only the named fields,
and those fields can be accessed directly.

Method definitions take the form:

(methodname [args*] body)

The argument and return types can be hinted on the arg and
methodname symbols. If not supplied, they will be inferred, so type
hints should be reserved for disambiguation.

Methods should be supplied for all methods of the desired
protocol(s) and interface(s). You can also define overrides for
methods of Object. Note that a parameter must be supplied to
correspond to the target object ('this' in Java parlance). Thus
methods for interfaces will take one more argument than do the
interface declarations. Note also that recur calls to the method
head should *not* pass the target object, it will be supplied
automatically and can not be substituted.

In the method bodies, the (unqualified) name can be used to name the
class (for calls to new, instance? etc).

The class will have implementations of several (clojure.lang)
interfaces generated automatically: IObj (metadata support) and
IPersistentMap, and all of their superinterfaces.

In addition, defrecord will define type-and-value-based =,
and will defined Java .hashCode and .equals consistent with the
contract for java.util.Map.

When AOT compiling, generates compiled bytecode for a class with the
given name (a symbol), prepends the current ns as the package, and
writes the .class file to the *compile-path* directory.

Two constructors will be defined, one taking the designated fields
followed by a metadata map (nil for none) and an extension field
map (nil for none), and one taking only the fields (using nil for
meta and extension fields). Note that the field names __meta
and __extmap are currently reserved and should not be used when
defining your own records.

Given (defrecord TypeName ...), two factory functions will be
defined: ->TypeName, taking positional parameters for the fields,
and map->TypeName, taking a map of keywords to field values.

Added in Clojure version 1.2
Source

defstruct

macro

Usage: (defstruct name & keys)

Same as (def name (create-struct keys...))

Added in Clojure version 1.0
Source

deftype

macro

Usage: (deftype name [& fields] & opts+specs)

(deftype name [fields*]  options* specs*)

Currently there are no options.

Each spec consists of a protocol or interface name followed by zero
or more method bodies:

protocol-or-interface-or-Object
(methodName [args*] body)*

Dynamically generates compiled bytecode for class with the given
name, in a package with the same name as the current namespace, the
given fields, and, optionally, methods for protocols and/or
interfaces. 

The class will have the (by default, immutable) fields named by
fields, which can have type hints. Protocols/interfaces and methods
are optional. The only methods that can be supplied are those
declared in the protocols/interfaces.  Note that method bodies are
not closures, the local environment includes only the named fields,
and those fields can be accessed directy. Fields can be qualified
with the metadata :volatile-mutable true or :unsynchronized-mutable
true, at which point (set! afield aval) will be supported in method
bodies. Note well that mutable fields are extremely difficult to use
correctly, and are present only to facilitate the building of higher
level constructs, such as Clojure's reference types, in Clojure
itself. They are for experts only - if the semantics and
implications of :volatile-mutable or :unsynchronized-mutable are not
immediately apparent to you, you should not be using them.

Method definitions take the form:

(methodname [args*] body)

The argument and return types can be hinted on the arg and
methodname symbols. If not supplied, they will be inferred, so type
hints should be reserved for disambiguation.

Methods should be supplied for all methods of the desired
protocol(s) and interface(s). You can also define overrides for
methods of Object. Note that a parameter must be supplied to
correspond to the target object ('this' in Java parlance). Thus
methods for interfaces will take one more argument than do the
interface declarations. Note also that recur calls to the method
head should *not* pass the target object, it will be supplied
automatically and can not be substituted.

In the method bodies, the (unqualified) name can be used to name the
class (for calls to new, instance? etc).

When AOT compiling, generates compiled bytecode for a class with the
given name (a symbol), prepends the current ns as the package, and
writes the .class file to the *compile-path* directory.

One constructor will be defined, taking the designated fields.  Note
that the field names __meta and __extmap are currently reserved and
should not be used when defining your own types.

Given (deftype TypeName ...), a factory function called ->TypeName
will be defined, taking positional parameters for the fields

Added in Clojure version 1.2
Source

delay

macro

Usage: (delay & body)

Takes a body of expressions and yields a Delay object that will
invoke the body only the first time it is forced (with force or deref/@), and
will cache the result and return it on all subsequent force
calls. See also - realized?

Added in Clojure version 1.0
Source

delay?

function

Usage: (delay? x)

returns true if x is a Delay created with delay

Added in Clojure version 1.0
Source

deliver

function

Usage: (deliver promise val)

Delivers the supplied value to the promise, releasing any pending
derefs. A subsequent call to deliver on a promise will have no effect.

Added in Clojure version 1.1
Source

denominator

function

Usage: (denominator r)

Returns the denominator part of a Ratio.

Added in Clojure version 1.2
Source

deref

function

Usage: (deref ref)
       (deref ref timeout-ms timeout-val)

Also reader macro: @ref/@agent/@var/@atom/@delay/@future/@promise. Within a transaction,
returns the in-transaction-value of ref, else returns the
most-recently-committed value of ref. When applied to a var, agent
or atom, returns its current state. When applied to a delay, forces
it if not already forced. When applied to a future, will block if
computation not complete. When applied to a promise, will block
until a value is delivered.  The variant taking a timeout can be
used for blocking references (futures and promises), and will return
timeout-val if the timeout (in milliseconds) is reached before a
value is available. See also - realized?.

Added in Clojure version 1.0
Source

derive

function

Usage: (derive tag parent)
       (derive h tag parent)

Establishes a parent/child relationship between parent and
tag. Parent must be a namespace-qualified symbol or keyword and
child can be either a namespace-qualified symbol or keyword or a
class. h must be a hierarchy obtained from make-hierarchy, if not
supplied defaults to, and modifies, the global hierarchy.

Added in Clojure version 1.0
Source

descendants

function

Usage: (descendants tag)
       (descendants h tag)

Returns the immediate and indirect children of tag, through a
relationship established via derive. h must be a hierarchy obtained
from make-hierarchy, if not supplied defaults to the global
hierarchy. Note: does not work on Java type inheritance
relationships.

Added in Clojure version 1.0
Source

disj

function

Usage: (disj set)
       (disj set key)
       (disj set key & ks)

disj[oin]. Returns a new set of the same (hashed/sorted) type, that
does not contain key(s).

Added in Clojure version 1.0
Source

disj!

function

Usage: (disj! set)
       (disj! set key)
       (disj! set key & ks)

disj[oin]. Returns a transient set of the same (hashed/sorted) type, that
does not contain key(s).

Added in Clojure version 1.1
Source

dissoc

function

Usage: (dissoc map)
       (dissoc map key)
       (dissoc map key & ks)

dissoc[iate]. Returns a new map of the same (hashed/sorted) type,
that does not contain a mapping for key(s).

Added in Clojure version 1.0
Source

dissoc!

function

Usage: (dissoc! map key)
       (dissoc! map key & ks)

Returns a transient map that doesn't contain a mapping for key(s).

Added in Clojure version 1.1
Source

distinct

function

Usage: (distinct coll)

Returns a lazy sequence of the elements of coll with duplicates removed

Added in Clojure version 1.0
Source

distinct?

function

Usage: (distinct? x)
       (distinct? x y)
       (distinct? x y & more)

Returns true if no two of the arguments are =

Added in Clojure version 1.0
Source

do

special form

Usage: (do exprs*)

Evaluates the expressions in order and returns the value of
the last. If no expressions are supplied, returns nil.

Please see https://clojure.org/reference/special_forms#do

Added in Clojure version 1.0

doall

function

Usage: (doall coll)
       (doall n coll)

When lazy sequences are produced via functions that have side
effects, any effects other than those needed to produce the first
element in the seq do not occur until the seq is consumed. doall can
be used to force any effects. Walks through the successive nexts of
the seq, retains the head and returns it, thus causing the entire
seq to reside in memory at one time.

Added in Clojure version 1.0
Source

dorun

function

Usage: (dorun coll)
       (dorun n coll)

When lazy sequences are produced via functions that have side
effects, any effects other than those needed to produce the first
element in the seq do not occur until the seq is consumed. dorun can
be used to force any effects. Walks through the successive nexts of
the seq, does not retain the head and returns nil.

Added in Clojure version 1.0
Source

doseq

macro

Usage: (doseq seq-exprs & body)

Repeatedly executes body (presumably for side-effects) with
bindings and filtering as provided by "for".  Does not retain
the head of the sequence. Returns nil.

Added in Clojure version 1.0
Source

dosync

macro

Usage: (dosync & exprs)

Runs the exprs (in an implicit do) in a transaction that encompasses
exprs and any nested calls.  Starts a transaction if none is already
running on this thread. Any uncaught exception will abort the
transaction and flow out of dosync. The exprs may be run more than
once, but any effects on Refs will be atomic.

Added in Clojure version 1.0
Source

dotimes

macro

Usage: (dotimes bindings & body)

bindings => name n

Repeatedly executes body (presumably for side-effects) with name
bound to integers from 0 through n-1.

Added in Clojure version 1.0
Source

doto

macro

Usage: (doto x & forms)

Evaluates x then calls all of the methods and functions with the
value of x supplied at the front of the given arguments.  The forms
are evaluated in order.  Returns x.

(doto (new java.util.HashMap) (.put "a" 1) (.put "b" 2))

Added in Clojure version 1.0
Source

double

function

Usage: (double x)

Coerce to double

Added in Clojure version 1.0
Source

double-array

function

Usage: (double-array size-or-seq)
       (double-array size init-val-or-seq)

Creates an array of doubles

Added in Clojure version 1.0
Source

doubles

function

Usage: (doubles xs)

Casts to double[]

Added in Clojure version 1.0
Source

drop

function

Usage: (drop n coll)

Returns a lazy sequence of all but the first n items in coll.

Added in Clojure version 1.0
Source

drop-last

function

Usage: (drop-last s)
       (drop-last n s)

Return a lazy sequence of all but the last n (default 1) items in coll

Added in Clojure version 1.0
Source

drop-while

function

Usage: (drop-while pred coll)

Returns a lazy sequence of the items in coll starting from the first
item for which (pred item) returns logical false.

Added in Clojure version 1.0
Source

empty

function

Usage: (empty coll)

Returns an empty collection of the same category as coll, or nil

Added in Clojure version 1.0
Source

empty?

function

Usage: (empty? coll)

Returns true if coll has no items - same as (not (seq coll)).
Please use the idiom (seq x) rather than (not (empty? x))

Added in Clojure version 1.0
Source

ensure

function

Usage: (ensure ref)

Must be called in a transaction. Protects the ref from modification
by other transactions.  Returns the in-transaction-value of
ref. Allows for more concurrency than (ref-set ref @ref)

Added in Clojure version 1.0
Source

enumeration-seq

function

Usage: (enumeration-seq e)

Returns a seq on a java.util.Enumeration

Added in Clojure version 1.0
Source

error-handler

function

Usage: (error-handler a)

Returns the error-handler of agent a, or nil if there is none.
See set-error-handler!

Added in Clojure version 1.2
Source

error-mode

function

Usage: (error-mode a)

Returns the error-mode of agent a.  See set-error-mode!

Added in Clojure version 1.2
Source

eval

function

Usage: (eval form)

Evaluates the form data structure (not text!) and returns the result.

Added in Clojure version 1.0
Source

even?

function

Usage: (even? n)

Returns true if n is even, throws an exception if n is not an integer

Added in Clojure version 1.0
Source

every-pred

function

Usage: (every-pred p)
       (every-pred p1 p2)
       (every-pred p1 p2 p3)
       (every-pred p1 p2 p3 & ps)

Takes a set of predicates and returns a function f that returns true if all of its
composing predicates return a logical true value against all of its arguments, else it returns
false. Note that f is short-circuiting in that it will stop execution on the first
argument that triggers a logical false result against the original predicates.

Added in Clojure version 1.3
Source

every?

function

Usage: (every? pred coll)

Returns true if (pred x) is logical true for every x in coll, else
false.

Added in Clojure version 1.0
Source

ex-data

function

Usage: (ex-data ex)

Returns exception data (a map) if ex is an IExceptionInfo.
Otherwise returns nil.

Added in Clojure version 1.4
Source

ex-info

function

Usage: (ex-info msg map)
       (ex-info msg map cause)

Create an instance of ExceptionInfo, a RuntimeException subclass
that carries a map of additional data.

Added in Clojure version 1.4
Source

extend

function

Usage: (extend atype & proto+mmaps)

Implementations of protocol methods can be provided using the extend construct:

 (extend AType
   AProtocol
    {:foo an-existing-fn
     :bar (fn [a b] ...)
     :baz (fn ([a]...) ([a b] ...)...)}
   BProtocol 
     {...} 
   ...)

 extend takes a type/class (or interface, see below), and one or more
 protocol + method map pairs. It will extend the polymorphism of the
 protocol's methods to call the supplied methods when an AType is
 provided as the first argument. 

 Method maps are maps of the keyword-ized method names to ordinary
 fns. This facilitates easy reuse of existing fns and fn maps, for
 code reuse/mixins without derivation or composition. You can extend
 an interface to a protocol. This is primarily to facilitate interop
 with the host (e.g. Java) but opens the door to incidental multiple
 inheritance of implementation since a class can inherit from more
 than one interface, both of which extend the protocol. It is TBD how
 to specify which impl to use. You can extend a protocol on nil.

 If you are supplying the definitions explicitly (i.e. not reusing
 exsting functions or mixin maps), you may find it more convenient to
 use the extend-type or extend-protocol macros.

 Note that multiple independent extend clauses can exist for the same
 type, not all protocols need be defined in a single extend call.

 See also:
 extends?, satisfies?, extenders

Added in Clojure version 1.2
Source

extend-protocol

macro

Usage: (extend-protocol p & specs)

Useful when you want to provide several implementations of the same
protocol all at once. Takes a single protocol and the implementation
of that protocol for one or more types. Expands into calls to
extend-type:

(extend-protocol Protocol
  AType
    (foo [x] ...)
    (bar [x y] ...)
  BType
    (foo [x] ...)
    (bar [x y] ...)
  AClass
    (foo [x] ...)
    (bar [x y] ...)
  nil
    (foo [x] ...)
    (bar [x y] ...))

expands into:

(do
 (clojure.core/extend-type AType Protocol 
   (foo [x] ...) 
   (bar [x y] ...))
 (clojure.core/extend-type BType Protocol 
   (foo [x] ...) 
   (bar [x y] ...))
 (clojure.core/extend-type AClass Protocol 
   (foo [x] ...) 
   (bar [x y] ...))
 (clojure.core/extend-type nil Protocol 
   (foo [x] ...) 
   (bar [x y] ...)))

Added in Clojure version 1.2
Source

extend-type

macro

Usage: (extend-type t & specs)

A macro that expands into an extend call. Useful when you are
supplying the definitions explicitly inline, extend-type
automatically creates the maps required by extend.  Propagates the
class as a type hint on the first argument of all fns.

(extend-type MyType 
  Countable
    (cnt [c] ...)
  Foo
    (bar [x y] ...)
    (baz ([x] ...) ([x y & zs] ...)))

expands into:

(extend MyType
 Countable
   {:cnt (fn [c] ...)}
 Foo
   {:baz (fn ([x] ...) ([x y & zs] ...))
    :bar (fn [x y] ...)})

Added in Clojure version 1.2
Source

extenders

function

Usage: (extenders protocol)

Returns a collection of the types explicitly extending protocol

Added in Clojure version 1.2
Source

extends?

function

Usage: (extends? protocol atype)

Returns true if atype extends protocol

Added in Clojure version 1.2
Source

false?

function

Usage: (false? x)

Returns true if x is the value false, false otherwise.

Added in Clojure version 1.0
Source

ffirst

function

Usage: (ffirst x)

Same as (first (first x))

Added in Clojure version 1.0
Source

file-seq

function

Usage: (file-seq dir)

A tree seq on java.io.Files

Added in Clojure version 1.0
Source

filter

function

Usage: (filter pred coll)

Returns a lazy sequence of the items in coll for which
(pred item) returns true. pred must be free of side-effects.

Added in Clojure version 1.0
Source

filterv

function

Usage: (filterv pred coll)

Returns a vector of the items in coll for which
(pred item) returns true. pred must be free of side-effects.

Added in Clojure version 1.4
Source

finally

special syntax

Syntax for use with try.

Please see https://clojure.org/reference/special_forms#try

Added in Clojure version 1.0

find

function

Usage: (find map key)

Returns the map entry for key, or nil if key not present.

Added in Clojure version 1.0
Source

find-keyword

function

Usage: (find-keyword name)
       (find-keyword ns name)

Returns a Keyword with the given namespace and name if one already
exists.  This function will not intern a new keyword. If the keyword
has not already been interned, it will return nil.  Do not use :
in the keyword strings, it will be added automatically.

Added in Clojure version 1.3
Source

find-ns

function

Usage: (find-ns sym)

Returns the namespace named by the symbol or nil if it doesn't exist.

Added in Clojure version 1.0
Source

find-var

function

Usage: (find-var sym)

Returns the global var named by the namespace-qualified symbol, or
nil if no var with that name.

Added in Clojure version 1.0
Source

first

function

Usage: (first coll)

Returns the first item in the collection. Calls seq on its
argument. If coll is nil, returns nil.

Added in Clojure version 1.0
Source

flatten

function

Usage: (flatten x)

Takes any nested combination of sequential things (lists, vectors,
etc.) and returns their contents as a single, flat sequence.
(flatten nil) returns an empty sequence.

Added in Clojure version 1.2
Source

float

function

Usage: (float x)

Coerce to float

Added in Clojure version 1.0
Source

float-array

function

Usage: (float-array size-or-seq)
       (float-array size init-val-or-seq)

Creates an array of floats

Added in Clojure version 1.0
Source

float?

function

Usage: (float? n)

Returns true if n is a floating point number

Added in Clojure version 1.0
Source

floats

function

Usage: (floats xs)

Casts to float[]

Added in Clojure version 1.0
Source

flush

function

Usage: (flush)

Flushes the output stream that is the current value of
*out*

Added in Clojure version 1.0
Source

fn

special form

Usage: (fn name? [params*] exprs*)
       (fn name? ([params*] exprs*) +)

params => positional-params* , or positional-params* & next-param
positional-param => binding-form
next-param => binding-form
name => symbol

Defines a function

Added in Clojure version 1.0
Source

fn?

function

Usage: (fn? x)

Returns true if x implements Fn, i.e. is an object created via fn.

Added in Clojure version 1.0
Source

fnext

function

Usage: (fnext x)

Same as (first (next x))

Added in Clojure version 1.0
Source

fnil

function

Usage: (fnil f x)
       (fnil f x y)
       (fnil f x y z)

Takes a function f, and returns a function that calls f, replacing
a nil first argument to f with the supplied value x. Higher arity
versions can replace arguments in the second and third
positions (y, z). Note that the function f can take any number of
arguments, not just the one(s) being nil-patched.

Added in Clojure version 1.2
Source

for

macro

Usage: (for seq-exprs body-expr)

List comprehension. Takes a vector of one or more
 binding-form/collection-expr pairs, each followed by zero or more
 modifiers, and yields a lazy sequence of evaluations of expr.
 Collections are iterated in a nested fashion, rightmost fastest,
 and nested coll-exprs can refer to bindings created in prior
 binding-forms.  Supported modifiers are: :let [binding-form expr ...],
 :while test, :when test.

(take 100 (for [x (range 100000000) y (range 1000000) :while (< y x)] [x y]))

Added in Clojure version 1.0
Source

force

function

Usage: (force x)

If x is a Delay, returns the (possibly cached) value of its expression, else returns x

Added in Clojure version 1.0
Source

format

function

Usage: (format fmt & args)

Formats a string using java.lang.String.format, see java.util.Formatter for format
string syntax

Added in Clojure version 1.0
Source

frequencies

function

Usage: (frequencies coll)

Returns a map from distinct items in coll to the number of times
they appear.

Added in Clojure version 1.2
Source

future

macro

Usage: (future & body)

Takes a body of expressions and yields a future object that will
invoke the body in another thread, and will cache the result and
return it on all subsequent calls to deref/@. If the computation has
not yet finished, calls to deref/@ will block, unless the variant of
deref with timeout is used. See also - realized?.

Added in Clojure version 1.1
Source

future-call

function

Usage: (future-call f)

Takes a function of no args and yields a future object that will
invoke the function in another thread, and will cache the result and
return it on all subsequent calls to deref/@. If the computation has
not yet finished, calls to deref/@ will block, unless the variant
of deref with timeout is used. See also - realized?.

Added in Clojure version 1.1
Source

future-cancel

function

Usage: (future-cancel f)

Cancels the future, if possible.

Added in Clojure version 1.1
Source

future-cancelled?

function

Usage: (future-cancelled? f)

Returns true if future f is cancelled

Added in Clojure version 1.1
Source

future-done?

function

Usage: (future-done? f)

Returns true if future f is done

Added in Clojure version 1.1
Source

future?

function

Usage: (future? x)

Returns true if x is a future

Added in Clojure version 1.1
Source

gen-class

macro

Usage: (gen-class & options)

When compiling, generates compiled bytecode for a class with the
given package-qualified :name (which, as all names in these
parameters, can be a string or symbol), and writes the .class file
to the *compile-path* directory.  When not compiling, does
nothing. The gen-class construct contains no implementation, as the
implementation will be dynamically sought by the generated class in
functions in an implementing Clojure namespace. Given a generated
class org.mydomain.MyClass with a method named mymethod, gen-class
will generate an implementation that looks for a function named by 
(str prefix mymethod) (default prefix: "-") in a
Clojure namespace specified by :impl-ns
(defaults to the current namespace). All inherited methods,
generated methods, and init and main functions (see :methods, :init,
and :main below) will be found similarly prefixed. By default, the
static initializer for the generated class will attempt to load the
Clojure support code for the class as a resource from the classpath,
e.g. in the example case, ``org/mydomain/MyClass__init.class``. This
behavior can be controlled by :load-impl-ns

Note that methods with a maximum of 18 parameters are supported.

In all subsequent sections taking types, the primitive types can be
referred to by their Java names (int, float etc), and classes in the
java.lang package can be used without a package qualifier. All other
classes must be fully qualified.

Options should be a set of key/value pairs, all except for :name are optional:

:name aname

The package-qualified name of the class to be generated

:extends aclass

Specifies the superclass, the non-private methods of which will be
overridden by the class. If not provided, defaults to Object.

:implements [interface ...]

One or more interfaces, the methods of which will be implemented by the class.

:init name

If supplied, names a function that will be called with the arguments
to the constructor. Must return [ [superclass-constructor-args] state] 
If not supplied, the constructor args are passed directly to
the superclass constructor and the state will be nil

:constructors {[param-types] [super-param-types], ...}

By default, constructors are created for the generated class which
match the signature(s) of the constructors for the superclass. This
parameter may be used to explicitly specify constructors, each entry
providing a mapping from a constructor signature to a superclass
constructor signature. When you supply this, you must supply an :init
specifier. 

:post-init name

If supplied, names a function that will be called with the object as
the first argument, followed by the arguments to the constructor.
It will be called every time an object of this class is created,
immediately after all the inherited constructors have completed.
It's return value is ignored.

:methods [ [name [param-types] return-type], ...]

The generated class automatically defines all of the non-private
methods of its superclasses/interfaces. This parameter can be used
to specify the signatures of additional methods of the generated
class. Static methods can be specified with ^{:static true} in the
signature's metadata. Do not repeat superclass/interface signatures
here.

:main boolean

If supplied and true, a static public main function will be generated. It will
pass each string of the String[] argument as a separate argument to
a function called (str prefix main).

:factory name

If supplied, a (set of) public static factory function(s) will be
created with the given name, and the same signature(s) as the
constructor(s).

:state name

If supplied, a public final instance field with the given name will be
created. You must supply an :init function in order to provide a
value for the state. Note that, though final, the state can be a ref
or agent, supporting the creation of Java objects with transactional
or asynchronous mutation semantics.

:exposes {protected-field-name {:get name :set name}, ...}

Since the implementations of the methods of the generated class
occur in Clojure functions, they have no access to the inherited
protected fields of the superclass. This parameter can be used to
generate public getter/setter methods exposing the protected field(s)
for use in the implementation.

:exposes-methods {super-method-name exposed-name, ...}

It is sometimes necessary to call the superclass' implementation of an
overridden method.  Those methods may be exposed and referred in 
the new method implementation by a local name.

:prefix string

Default: "-" Methods called e.g. Foo will be looked up in vars called
prefixFoo in the implementing ns.

:impl-ns name

Default: the name of the current ns. Implementations of methods will be 
looked up in this namespace.

:load-impl-ns boolean

Default: true. Causes the static initializer for the generated class
to reference the load code for the implementing namespace. Should be
true when implementing-ns is the default, false if you intend to
load the code via some other method.

Added in Clojure version 1.0
Source

gen-interface

macro

Usage: (gen-interface & options)

When compiling, generates compiled bytecode for an interface with
 the given package-qualified :name (which, as all names in these
 parameters, can be a string or symbol), and writes the .class file
 to the *compile-path* directory.  When not compiling, does nothing.

 In all subsequent sections taking types, the primitive types can be
 referred to by their Java names (int, float etc), and classes in the
 java.lang package can be used without a package qualifier. All other
 classes must be fully qualified.

 Options should be a set of key/value pairs, all except for :name are
 optional:

 :name aname

 The package-qualified name of the class to be generated

 :extends [interface ...]

 One or more interfaces, which will be extended by this interface.

 :methods [ [name [param-types] return-type], ...]

 This parameter is used to specify the signatures of the methods of
 the generated interface.  Do not repeat superinterface signatures
 here.

Added in Clojure version 1.0
Source

gensym

function

Usage: (gensym)
       (gensym prefix-string)

Returns a new symbol with a unique name. If a prefix string is
supplied, the name is prefix# where # is some unique number. If
prefix is not supplied, the prefix is 'G__'.

Added in Clojure version 1.0
Source

get

function

Usage: (get map key)
       (get map key not-found)

Returns the value mapped to key, not-found or nil if key not present.

Added in Clojure version 1.0
Source

get-in

function

Usage: (get-in m ks)
       (get-in m ks not-found)

Returns the value in a nested associative structure,
where ks is a sequence of keys. Returns nil if the key
is not present, or the not-found value if supplied.

Added in Clojure version 1.2
Source

get-method

function

Usage: (get-method multifn dispatch-val)

Given a multimethod and a dispatch value, returns the dispatch fn
that would apply to that value, or nil if none apply and no default

Added in Clojure version 1.0
Source

get-proxy-class

function

Usage: (get-proxy-class & bases)

Takes an optional single class followed by zero or more
interfaces. If not supplied class defaults to Object.  Creates an
returns an instance of a proxy class derived from the supplied
classes. The resulting value is cached and used for any subsequent
requests for the same class set. Returns a Class object.

Added in Clojure version 1.0
Source

get-thread-bindings

function

Usage: (get-thread-bindings)

Get a map with the Var/value pairs which is currently in effect for the
current thread.

Added in Clojure version 1.1
Source

get-validator

function

Usage: (get-validator iref)

Gets the validator-fn for a var/ref/agent/atom.

Added in Clojure version 1.0
Source

group-by

function

Usage: (group-by f coll)

Returns a map of the elements of coll keyed by the result of
f on each element. The value at each key will be a vector of the
corresponding elements, in the order they appeared in coll.

Added in Clojure version 1.2
Source

hash

function

Usage: (hash x)

Returns the hash code of its argument. Note this is the hash code
consistent with =, and thus is different than .hashCode for Integer,
Short, Byte and Clojure collections.

Added in Clojure version 1.0
Source

hash-map

function

Usage: (hash-map)
       (hash-map & keyvals)

keyval => key val
Returns a new hash map with supplied mappings.  If any keys are
equal, they are handled as if by repeated uses of assoc.

Added in Clojure version 1.0
Source

hash-ordered-coll

function

Usage: (hash-ordered-coll coll)

Returns the hash code, consistent with =, for an external ordered
collection implementing Iterable.
See http://clojure.org/data_structures#hash for full algorithms.

Added in Clojure version 1.6
Source

hash-set

function

Usage: (hash-set)
       (hash-set & keys)

Returns a new hash set with supplied keys.  Any equal keys are
handled as if by repeated uses of conj.

Added in Clojure version 1.0
Source

hash-unordered-coll

function

Usage: (hash-unordered-coll coll)

Returns the hash code, consistent with =, for an external unordered
collection implementing Iterable. For maps, the iterator should
return map entries whose hash is computed as
  (hash-ordered-coll [k v]).
See http://clojure.org/data_structures#hash for full algorithms.

Added in Clojure version 1.6
Source

identical?

function

Usage: (identical? x y)

Tests if 2 arguments are the same object

Added in Clojure version 1.0
Source

identity

function

Usage: (identity x)

Returns its argument.

Added in Clojure version 1.0
Source

if

special form

Usage: (if test then else?)

Evaluates test. If not the singular values nil or false,
evaluates and yields then, otherwise, evaluates and yields else. If
else is not supplied it defaults to nil.

Please see https://clojure.org/reference/special_forms#if

Added in Clojure version 1.0

if-let

macro

Usage: (if-let bindings then)
       (if-let bindings then else & oldform)

bindings => binding-form test

If test is true, evaluates then with binding-form bound to the value of 
test, if not, yields else

Added in Clojure version 1.0
Source

if-not

macro

Usage: (if-not test then)
       (if-not test then else)

Evaluates test. If logical false, evaluates and returns then expr, 
otherwise else expr, if supplied, else nil.

Added in Clojure version 1.0
Source

if-some

macro

Usage: (if-some bindings then)
       (if-some bindings then else & oldform)

bindings => binding-form test

If test is not nil, evaluates then with binding-form bound to the
value of test, if not, yields else

Added in Clojure version 1.6
Source

ifn?

function

Usage: (ifn? x)

Returns true if x implements IFn. Note that many data structures
(e.g. sets and maps) implement IFn

Added in Clojure version 1.0
Source

import

macro

Usage: (import & import-symbols-or-lists)

import-list => (package-symbol class-name-symbols*)

For each name in class-name-symbols, adds a mapping from name to the
class named by package.name to the current namespace. Use :import in the ns
macro in preference to calling this directly.

Added in Clojure version 1.0
Source

in-ns

function

Usage: (in-ns name)

Sets *ns* to the namespace named by the symbol, creating it if needed.

Added in Clojure version 1.0

inc

function

Usage: (inc x)

Returns a number one greater than num. Does not auto-promote
longs, will throw on overflow. See also: inc'

Added in Clojure version 1.2
Source

inc'

function

Usage: (inc' x)

Returns a number one greater than num. Supports arbitrary precision.
See also: inc

Added in Clojure version 1.0
Source

init-proxy

function

Usage: (init-proxy proxy mappings)

Takes a proxy instance and a map of strings (which must
correspond to methods of the proxy superclass/superinterfaces) to
fns (which must take arguments matching the corresponding method,
plus an additional (explicit) first arg corresponding to this, and
sets the proxy's fn map.  Returns the proxy.

Added in Clojure version 1.0
Source

instance?

function

Usage: (instance? c x)

Evaluates x and tests if it is an instance of the class
c. Returns true or false

Added in Clojure version 1.0
Source

int

function

Usage: (int x)

Coerce to int

Added in Clojure version 1.0
Source

int-array

function

Usage: (int-array size-or-seq)
       (int-array size init-val-or-seq)

Creates an array of ints

Added in Clojure version 1.0
Source

integer?

function

Usage: (integer? n)

Returns true if n is an integer

Added in Clojure version 1.0
Source

interleave

function

Usage: (interleave)
       (interleave c1)
       (interleave c1 c2)
       (interleave c1 c2 & colls)

Returns a lazy seq of the first item in each coll, then the second etc.

Added in Clojure version 1.0
Source

intern

function

Usage: (intern ns name)
       (intern ns name val)

Finds or creates a var named by the symbol name in the namespace
ns (which can be a symbol or a namespace), setting its root binding
to val if supplied. The namespace must exist. The var will adopt any
metadata from the name symbol.  Returns the var.

Added in Clojure version 1.0
Source

interpose

function

Usage: (interpose sep coll)

Returns a lazy seq of the elements of coll separated by sep

Added in Clojure version 1.0
Source

into

function

Usage: (into to from)

Returns a new coll consisting of to-coll with all of the items of
from-coll conjoined.

Added in Clojure version 1.0
Source

into-array

function

Usage: (into-array aseq)
       (into-array type aseq)

Returns an array with components set to the values in aseq. The array's
component type is type if provided, or the type of the first value in
aseq if present, or Object. All values in aseq must be compatible with
the component type. Class objects for the primitive types can be obtained
using, e.g., Integer/TYPE.

Added in Clojure version 1.0
Source

ints

function

Usage: (ints xs)

Casts to int[]

Added in Clojure version 1.0
Source

io!

macro

Usage: (io! & body)

If an io! block occurs in a transaction, throws an
IllegalStateException, else runs body in an implicit do. If the
first expression in body is a literal string, will use that as the
exception message.

Added in Clojure version 1.0
Source

isa?

function

Usage: (isa? child parent)
       (isa? h child parent)

Returns true if (= child parent), or child is directly or indirectly derived from
parent, either via a Java type inheritance relationship or a
relationship established via derive. h must be a hierarchy obtained
from make-hierarchy, if not supplied defaults to the global
hierarchy

Added in Clojure version 1.0
Source

iterate

function

Usage: (iterate f x)

Returns a lazy sequence of x, (f x), (f (f x)) etc. f must be free of side-effects

Added in Clojure version 1.0
Source

iterator-seq

function

Usage: (iterator-seq iter)

Returns a seq on a java.util.Iterator. Note that most collections
providing iterators implement Iterable and thus support seq directly.

Added in Clojure version 1.0
Source

juxt

function

Usage: (juxt f)
       (juxt f g)
       (juxt f g h)
       (juxt f g h & fs)

Takes a set of functions and returns a fn that is the juxtaposition
of those fns.  The returned fn takes a variable number of args, and
returns a vector containing the result of applying each fn to the
args (left-to-right).
((juxt a b c) x) => [(a x) (b x) (c x)]

Added in Clojure version 1.1
Source

keep

function

Usage: (keep f coll)

Returns a lazy sequence of the non-nil results of (f item). Note,
this means false return values will be included.  f must be free of
side-effects.

Added in Clojure version 1.2
Source

keep-indexed

function

Usage: (keep-indexed f coll)

Returns a lazy sequence of the non-nil results of (f index item). Note,
this means false return values will be included.  f must be free of
side-effects.

Added in Clojure version 1.2
Source

key

function

Usage: (key e)

Returns the key of the map entry.

Added in Clojure version 1.0
Source

keys

function

Usage: (keys map)

Returns a sequence of the map's keys, in the same order as (seq map).

Added in Clojure version 1.0
Source

keyword

function

Usage: (keyword name)
       (keyword ns name)

Returns a Keyword with the given namespace and name.  Do not use :
in the keyword strings, it will be added automatically.

Added in Clojure version 1.0
Source

keyword?

function

Usage: (keyword? x)

Return true if x is a Keyword

Added in Clojure version 1.0
Source

last

function

Usage: (last coll)

Return the last item in coll, in linear time

Added in Clojure version 1.0
Source

lazy-cat

macro

Usage: (lazy-cat & colls)

Expands to code which yields a lazy sequence of the concatenation
of the supplied colls.  Each coll expr is not evaluated until it is
needed. 

(lazy-cat xs ys zs) === (concat (lazy-seq xs) (lazy-seq ys) (lazy-seq zs))

Added in Clojure version 1.0
Source

lazy-seq

macro

Usage: (lazy-seq & body)

Takes a body of expressions that returns an ISeq or nil, and yields
a Seqable object that will invoke the body only the first time seq
is called, and will cache the result and return it on all subsequent
seq calls. See also - realized?

Added in Clojure version 1.0
Source

let

special form

Usage: (let [bindings*] exprs*)

binding => binding-form init-expr

Evaluates the exprs in a lexical context in which the symbols in
the binding-forms are bound to their respective init-exprs or parts
therein.

Added in Clojure version 1.0
Source

letfn

special form

Usage: (letfn [fnspecs*] exprs*)

fnspec ==> (fname [params*] exprs) or (fname ([params*] exprs)+)

Takes a vector of function specs and a body, and generates a set of
bindings of functions to their names. All of the names are available
in all of the definitions of the functions, as well as the body.

Added in Clojure version 1.0
Source

line-seq

function

Usage: (line-seq rdr)

Returns the lines of text from rdr as a lazy sequence of strings.
rdr must implement java.io.BufferedReader.

Added in Clojure version 1.0
Source

list

function

Usage: (list & items)

Creates a new list containing the items.

Added in Clojure version 1.0
Source

list*

function

Usage: (list* args)
       (list* a args)
       (list* a b args)
       (list* a b c args)
       (list* a b c d & more)

Creates a new list containing the items prepended to the rest, the
last of which will be treated as a sequence.

Added in Clojure version 1.0
Source

list?

function

Usage: (list? x)

Returns true if x implements IPersistentList

Added in Clojure version 1.0
Source

load

function

Usage: (load & paths)

Loads Clojure code from resources in classpath. A path is interpreted as
classpath-relative if it begins with a slash or relative to the root
directory for the current namespace otherwise.

Added in Clojure version 1.0
Source

load-file

function

Usage: (load-file name)

Sequentially read and evaluate the set of forms contained in the file.

Added in Clojure version 1.0

load-reader

function

Usage: (load-reader rdr)

Sequentially read and evaluate the set of forms contained in the
stream/file

Added in Clojure version 1.0
Source

load-string

function

Usage: (load-string s)

Sequentially read and evaluate the set of forms contained in the
string

Added in Clojure version 1.0
Source

loaded-libs

function

Usage: (loaded-libs)

Returns a sorted set of symbols naming the currently loaded libs

Added in Clojure version 1.0
Source

locking

macro

Usage: (locking x & body)

Executes exprs in an implicit do, while holding the monitor of x.
Will release the monitor of x in all circumstances.

Added in Clojure version 1.0
Source

long

function

Usage: (long x)

Coerce to long

Added in Clojure version 1.0
Source

long-array

function

Usage: (long-array size-or-seq)
       (long-array size init-val-or-seq)

Creates an array of longs

Added in Clojure version 1.0
Source

longs

function

Usage: (longs xs)

Casts to long[]

Added in Clojure version 1.0
Source

loop

special form

Usage: (loop [bindings*] exprs*)

Evaluates the exprs in a lexical context in which the symbols in
the binding-forms are bound to their respective init-exprs or parts
therein. Acts as a recur target.

Added in Clojure version 1.0
Source

macroexpand

function

Usage: (macroexpand form)

Repeatedly calls macroexpand-1 on form until it no longer
represents a macro form, then returns it.  Note neither
macroexpand-1 nor macroexpand expand macros in subforms.

Added in Clojure version 1.0
Source

macroexpand-1

function

Usage: (macroexpand-1 form)

If form represents a macro form, returns its expansion,
else returns form.

Added in Clojure version 1.0
Source

make-array

function

Usage: (make-array type len)
       (make-array type dim & more-dims)

Creates and returns an array of instances of the specified class of
the specified dimension(s).  Note that a class object is required.
Class objects can be obtained by using their imported or
fully-qualified name.  Class objects for the primitive types can be
obtained using, e.g., Integer/TYPE.

Added in Clojure version 1.0
Source

make-hierarchy

function

Usage: (make-hierarchy)

Creates a hierarchy object for use with derive, isa? etc.

Added in Clojure version 1.0
Source

map

function

Usage: (map f coll)
       (map f c1 c2)
       (map f c1 c2 c3)
       (map f c1 c2 c3 & colls)

Returns a lazy sequence consisting of the result of applying f to the
set of first items of each coll, followed by applying f to the set
of second items in each coll, until any one of the colls is
exhausted.  Any remaining items in other colls are ignored. Function
f should accept number-of-colls arguments.

Added in Clojure version 1.0
Source

map-indexed

function

Usage: (map-indexed f coll)

Returns a lazy sequence consisting of the result of applying f to 0
and the first item of coll, followed by applying f to 1 and the second
item in coll, etc, until coll is exhausted. Thus function f should
accept 2 arguments, index and item.

Added in Clojure version 1.2
Source

map?

function

Usage: (map? x)

Return true if x implements IPersistentMap

Added in Clojure version 1.0
Source

mapcat

function

Usage: (mapcat f & colls)

Returns the result of applying concat to the result of applying map
to f and colls.  Thus function f should return a collection.

Added in Clojure version 1.0
Source

mapv

function

Usage: (mapv f coll)
       (mapv f c1 c2)
       (mapv f c1 c2 c3)
       (mapv f c1 c2 c3 & colls)

Returns a vector consisting of the result of applying f to the
set of first items of each coll, followed by applying f to the set
of second items in each coll, until any one of the colls is
exhausted.  Any remaining items in other colls are ignored. Function
f should accept number-of-colls arguments.

Added in Clojure version 1.4
Source

max

function

Usage: (max x)
       (max x y)
       (max x y & more)

Returns the greatest of the nums.

Added in Clojure version 1.0
Source

max-key

function

Usage: (max-key k x)
       (max-key k x y)
       (max-key k x y & more)

Returns the x for which (k x), a number, is greatest.

Added in Clojure version 1.0
Source

memfn

macro

Usage: (memfn name & args)

Expands into code that creates a fn that expects to be passed an
object and any args and calls the named instance method on the
object passing the args. Use when you want to treat a Java method as
a first-class fn. name may be type-hinted with the method receiver's
type in order to avoid reflective calls.

Added in Clojure version 1.0
Source

memoize

function

Usage: (memoize f)

Returns a memoized version of a referentially transparent function. The
memoized version of the function keeps a cache of the mapping from arguments
to results and, when calls with the same arguments are repeated often, has
higher performance at the expense of higher memory use.

Added in Clojure version 1.0
Source

merge

function

Usage: (merge & maps)

Returns a map that consists of the rest of the maps conj-ed onto
the first.  If a key occurs in more than one map, the mapping from
the latter (left-to-right) will be the mapping in the result.

Added in Clojure version 1.0
Source

merge-with

function

Usage: (merge-with f & maps)

Returns a map that consists of the rest of the maps conj-ed onto
the first.  If a key occurs in more than one map, the mapping(s)
from the latter (left-to-right) will be combined with the mapping in
the result by calling (f val-in-result val-in-latter).

Added in Clojure version 1.0
Source

methods

function

Usage: (methods multifn)

Given a multimethod, returns a map of dispatch values -> dispatch fns

Added in Clojure version 1.0
Source

min

function

Usage: (min x)
       (min x y)
       (min x y & more)

Returns the least of the nums.

Added in Clojure version 1.0
Source

min-key

function

Usage: (min-key k x)
       (min-key k x y)
       (min-key k x y & more)

Returns the x for which (k x), a number, is least.

Added in Clojure version 1.0
Source

mix-collection-hash

function

Usage: (mix-collection-hash hash-basis count)

Mix final collection hash for ordered or unordered collections.
hash-basis is the combined collection hash, count is the number
of elements included in the basis. Note this is the hash code
consistent with =, different from .hashCode.
See http://clojure.org/data_structures#hash for full algorithms.

Added in Clojure version 1.6
Source

mod

function

Usage: (mod num div)

Modulus of num and div. Truncates toward negative infinity.

Added in Clojure version 1.0
Source

monitor-enter

special form

Usage: (monitor-enter x)

Synchronization primitive that should be avoided
in user code. Use the 'locking' macro.

Please see https://clojure.org/reference/special_forms#monitor-enter

Added in Clojure version 1.0

monitor-exit

special form

Usage: (monitor-exit x)

Synchronization primitive that should be avoided
in user code. Use the 'locking' macro.

Please see https://clojure.org/reference/special_forms#monitor-exit

Added in Clojure version 1.0

name

function

Usage: (name x)

Returns the name String of a string, symbol or keyword.

Added in Clojure version 1.0
Source

namespace

function

Usage: (namespace x)

Returns the namespace String of a symbol or keyword, or nil if not present.

Added in Clojure version 1.0
Source

namespace-munge

function

Usage: (namespace-munge ns)

Convert a Clojure namespace name to a legal Java package name.

Added in Clojure version 1.2
Source

neg?

function

Usage: (neg? x)

Returns true if num is less than zero, else false

Added in Clojure version 1.0
Source

new

special form

Usage: (Classname. args*)
       (new Classname args*)

The args, if any, are evaluated from left to right, and
passed to the constructor of the class named by Classname. The
constructed object is returned.

Please see https://clojure.org/java_interop#new

Added in Clojure version 1.0

newline

function

Usage: (newline)

Writes a platform-specific newline to *out*

Added in Clojure version 1.0
Source

function

Usage: (next coll)

Returns a seq of the items after the first. Calls seq on its
argument.  If there are no more items, returns nil.

Added in Clojure version 1.0
Source

nfirst

function

Usage: (nfirst x)

Same as (next (first x))

Added in Clojure version 1.0
Source

nil?

function

Usage: (nil? x)

Returns true if x is nil, false otherwise.

Added in Clojure version 1.0
Source

nnext

function

Usage: (nnext x)

Same as (next (next x))

Added in Clojure version 1.0
Source

not

function

Usage: (not x)

Returns true if x is logical false, false otherwise.

Added in Clojure version 1.0
Source

not-any?

function

Usage: (not-any? pred coll)

Returns false if (pred x) is logical true for any x in coll,
else true.

Added in Clojure version 1.0
Source

not-empty

function

Usage: (not-empty coll)

If coll is empty, returns nil, else coll

Added in Clojure version 1.0
Source

not-every?

function

Usage: (not-every? pred coll)

Returns false if (pred x) is logical true for every x in
coll, else true.

Added in Clojure version 1.0
Source

not=

function

Usage: (not= x)
       (not= x y)
       (not= x y & more)

Same as (not (= obj1 obj2))

Added in Clojure version 1.0
Source

ns

macro

Usage: (ns name docstring? attr-map? references*)

Sets *ns* to the namespace named by name (unevaluated), creating it
if needed.  references can be zero or more of: (:refer-clojure ...)
(:require ...) (:use ...) (:import ...) (:load ...) (:gen-class)
with the syntax of refer-clojure/require/use/import/load/gen-class
respectively, except the arguments are unevaluated and need not be
quoted. (:gen-class ...), when supplied, defaults to :name
corresponding to the ns name, :main true, :impl-ns same as ns, and
:init-impl-ns true. All options of gen-class are
supported. The :gen-class directive is ignored when not
compiling. If :gen-class is not supplied, when compiled only an
nsname__init.class will be generated. If :refer-clojure is not used, a
default (refer 'clojure.core) is used.  Use of ns is preferred to
individual calls to in-ns/require/use/import:

(ns foo.bar
  (:refer-clojure :exclude [ancestors printf])
  (:require (clojure.contrib sql combinatorics))
  (:use (my.lib this that))
  (:import (java.util Date Timer Random)
           (java.sql Connection Statement)))

Added in Clojure version 1.0
Source

ns-aliases

function

Usage: (ns-aliases ns)

Returns a map of the aliases for the namespace.

Added in Clojure version 1.0
Source

ns-imports

function

Usage: (ns-imports ns)

Returns a map of the import mappings for the namespace.

Added in Clojure version 1.0
Source

ns-interns

function

Usage: (ns-interns ns)

Returns a map of the intern mappings for the namespace.

Added in Clojure version 1.0
Source

ns-map

function

Usage: (ns-map ns)

Returns a map of all the mappings for the namespace.

Added in Clojure version 1.0
Source

ns-name

function

Usage: (ns-name ns)

Returns the name of the namespace, a symbol.

Added in Clojure version 1.0
Source

ns-publics

function

Usage: (ns-publics ns)

Returns a map of the public intern mappings for the namespace.

Added in Clojure version 1.0
Source

ns-refers

function

Usage: (ns-refers ns)

Returns a map of the refer mappings for the namespace.

Added in Clojure version 1.0
Source

ns-resolve

function

Usage: (ns-resolve ns sym)
       (ns-resolve ns env sym)

Returns the var or Class to which a symbol will be resolved in the
namespace (unless found in the environment), else nil.  Note that
if the symbol is fully qualified, the var/Class to which it resolves
need not be present in the namespace.

Added in Clojure version 1.0
Source

ns-unalias

function

Usage: (ns-unalias ns sym)

Removes the alias for the symbol from the namespace.

Added in Clojure version 1.0
Source

ns-unmap

function

Usage: (ns-unmap ns sym)

Removes the mappings for the symbol from the namespace.

Added in Clojure version 1.0
Source

nth

function

Usage: (nth coll index)
       (nth coll index not-found)

Returns the value at the index. get returns nil if index out of
bounds, nth throws an exception unless not-found is supplied.  nth
also works for strings, Java arrays, regex Matchers and Lists, and,
in O(n) time, for sequences.

Added in Clojure version 1.0
Source

nthnext

function

Usage: (nthnext coll n)

Returns the nth next of coll, (seq coll) when n is 0.

Added in Clojure version 1.0
Source

nthrest

function

Usage: (nthrest coll n)

Returns the nth rest of coll, coll when n is 0.

Added in Clojure version 1.3
Source

num

function

Usage: (num x)

Coerce to Number

Added in Clojure version 1.0
Source

number?

function

Usage: (number? x)

Returns true if x is a Number

Added in Clojure version 1.0
Source

numerator

function

Usage: (numerator r)

Returns the numerator part of a Ratio.

Added in Clojure version 1.2
Source

object-array

function

Usage: (object-array size-or-seq)

Creates an array of objects

Added in Clojure version 1.2
Source

odd?

function

Usage: (odd? n)

Returns true if n is odd, throws an exception if n is not an integer

Added in Clojure version 1.0
Source

or

macro

Usage: (or)
       (or x)
       (or x & next)

Evaluates exprs one at a time, from left to right. If a form
returns a logical true value, or returns that value and doesn't
evaluate any of the other expressions, otherwise it returns the
value of the last expression. (or) returns nil.

Added in Clojure version 1.0
Source

parents

function

Usage: (parents tag)
       (parents h tag)

Returns the immediate parents of tag, either via a Java type
inheritance relationship or a relationship established via derive. h
must be a hierarchy obtained from make-hierarchy, if not supplied
defaults to the global hierarchy

Added in Clojure version 1.0
Source

partial

function

Usage: (partial f)
       (partial f arg1)
       (partial f arg1 arg2)
       (partial f arg1 arg2 arg3)
       (partial f arg1 arg2 arg3 & more)

Takes a function f and fewer than the normal arguments to f, and
returns a fn that takes a variable number of additional args. When
called, the returned function calls f with args + additional args.

Added in Clojure version 1.0
Source

partition

function

Usage: (partition n coll)
       (partition n step coll)
       (partition n step pad coll)

Returns a lazy sequence of lists of n items each, at offsets step
apart. If step is not supplied, defaults to n, i.e. the partitions
do not overlap. If a pad collection is supplied, use its elements as
necessary to complete last partition upto n items. In case there are
not enough padding elements, return a partition with less than n items.

Added in Clojure version 1.0
Source

partition-all

function

Usage: (partition-all n coll)
       (partition-all n step coll)

Returns a lazy sequence of lists like partition, but may include
partitions with fewer than n items at the end.

Added in Clojure version 1.2
Source

partition-by

function

Usage: (partition-by f coll)

Applies f to each value in coll, splitting it each time f returns
a new value.  Returns a lazy seq of partitions.

Added in Clojure version 1.2
Source

pcalls

function

Usage: (pcalls & fns)

Executes the no-arg fns in parallel, returning a lazy sequence of
their values

Added in Clojure version 1.0
Source

peek

function

Usage: (peek coll)

For a list or queue, same as first, for a vector, same as, but much
more efficient than, last. If the collection is empty, returns nil.

Added in Clojure version 1.0
Source

persistent!

function

Usage: (persistent! coll)

Returns a new, persistent version of the transient collection, in
constant time. The transient collection cannot be used after this
call, any such use will throw an exception.

Added in Clojure version 1.1
Source

pmap

function

Usage: (pmap f coll)
       (pmap f coll & colls)

Like map, except f is applied in parallel. Semi-lazy in that the
parallel computation stays ahead of the consumption, but doesn't
realize the entire result unless required. Only useful for
computationally intensive functions where the time of f dominates
the coordination overhead.

Added in Clojure version 1.0
Source

pop

function

Usage: (pop coll)

For a list or queue, returns a new list/queue without the first
item, for a vector, returns a new vector without the last item. If
the collection is empty, throws an exception.  Note - not the same
as next/butlast.

Added in Clojure version 1.0
Source

pop!

function

Usage: (pop! coll)

Removes the last item from a transient vector. If
the collection is empty, throws an exception. Returns coll

Added in Clojure version 1.1
Source

pop-thread-bindings

function

Usage: (pop-thread-bindings)

Pop one set of bindings pushed with push-binding before. It is an error to
pop bindings without pushing before.

Added in Clojure version 1.1
Source

pos?

function

Usage: (pos? x)

Returns true if num is greater than zero, else false

Added in Clojure version 1.0
Source

pr

dynamic function

Usage: (pr)
       (pr x)
       (pr x & more)

Prints the object(s) to the output stream that is the current value
of *out*.  Prints the object(s), separated by spaces if there is
more than one.  By default, pr and prn print in a way that objects
can be read by the reader

Added in Clojure version 1.0
Source

pr-str

function

Usage: (pr-str & xs)

pr to a string, returning it

Added in Clojure version 1.0
Source

prefer-method

function

Usage: (prefer-method multifn dispatch-val-x dispatch-val-y)

Causes the multimethod to prefer matches of dispatch-val-x over dispatch-val-y 
when there is a conflict

Added in Clojure version 1.0
Source

prefers

function

Usage: (prefers multifn)

Given a multimethod, returns a map of preferred value -> set of other values

Added in Clojure version 1.0
Source

print

function

Usage: (print & more)

Prints the object(s) to the output stream that is the current value
of *out*.  print and println produce output for human consumption.

Added in Clojure version 1.0
Source

print-str

function

Usage: (print-str & xs)

print to a string, returning it

Added in Clojure version 1.0
Source

printf

function

Usage: (printf fmt & args)

Prints formatted output, as per format

Added in Clojure version 1.0
Source

println

function

Usage: (println & more)

Same as print followed by (newline)

Added in Clojure version 1.0
Source

println-str

function

Usage: (println-str & xs)

println to a string, returning it

Added in Clojure version 1.0
Source

prn

function

Usage: (prn & more)

Same as pr followed by (newline). Observes *flush-on-newline*

Added in Clojure version 1.0
Source

prn-str

function

Usage: (prn-str & xs)

prn to a string, returning it

Added in Clojure version 1.0
Source

promise

function

Usage: (promise)

Returns a promise object that can be read with deref/@, and set,
once only, with deliver. Calls to deref/@ prior to delivery will
block, unless the variant of deref with timeout is used. All
subsequent derefs will return the same delivered value without
blocking. See also - realized?.

Added in Clojure version 1.1
Source

proxy

macro

Usage: (proxy class-and-interfaces args & fs)

class-and-interfaces - a vector of class names

args - a (possibly empty) vector of arguments to the superclass
constructor.

f => (name [params*] body) or
(name ([params*] body) ([params+] body) ...)

Expands to code which creates a instance of a proxy class that
implements the named class/interface(s) by calling the supplied
fns. A single class, if provided, must be first. If not provided it
defaults to Object.

The interfaces names must be valid interface types. If a method fn
is not provided for a class method, the superclass methd will be
called. If a method fn is not provided for an interface method, an
UnsupportedOperationException will be thrown should it be
called. Method fns are closures and can capture the environment in
which proxy is called. Each method fn takes an additional implicit
first arg, which is bound to 'this. Note that while method fns can
be provided to override protected methods, they have no other access
to protected members, nor to super, as these capabilities cannot be
proxied.

Added in Clojure version 1.0
Source

proxy-mappings

function

Usage: (proxy-mappings proxy)

Takes a proxy instance and returns the proxy's fn map.

Added in Clojure version 1.0
Source

proxy-super

macro

Usage: (proxy-super meth & args)

Use to call a superclass method in the body of a proxy method. 
Note, expansion captures 'this

Added in Clojure version 1.0
Source

push-thread-bindings

function

Usage: (push-thread-bindings bindings)

WARNING: This is a low-level function. Prefer high-level macros like
binding where ever possible.

Takes a map of Var/value pairs. Binds each Var to the associated value for
the current thread. Each call *MUST* be accompanied by a matching call to
pop-thread-bindings wrapped in a try-finally!

    (push-thread-bindings bindings)
    (try
      ...
      (finally
        (pop-thread-bindings)))

Added in Clojure version 1.1
Source

pvalues

macro

Usage: (pvalues & exprs)

Returns a lazy sequence of the values of the exprs, which are
evaluated in parallel

Added in Clojure version 1.0
Source

quot

function

Usage: (quot num div)

quot[ient] of dividing numerator by denominator.

Added in Clojure version 1.0
Source

quote

special form

Usage: (quote form)

Yields the unevaluated form.

Please see https://clojure.org/reference/special_forms#quote

Added in Clojure version 1.0

rand

function

Usage: (rand)
       (rand n)

Returns a random floating point number between 0 (inclusive) and
n (default 1) (exclusive).

Added in Clojure version 1.0
Source

rand-int

function

Usage: (rand-int n)

Returns a random integer between 0 (inclusive) and n (exclusive).

Added in Clojure version 1.0
Source

rand-nth

function

Usage: (rand-nth coll)

Return a random element of the (sequential) collection. Will have
the same performance characteristics as nth for the given
collection.

Added in Clojure version 1.2
Source

range

function

Usage: (range)
       (range end)
       (range start end)
       (range start end step)

Returns a lazy seq of nums from start (inclusive) to end
(exclusive), by step, where start defaults to 0, step to 1, and end to
infinity. When step is equal to 0, returns an infinite sequence of
start. When start is equal to end, returns empty list.

Added in Clojure version 1.0
Source

ratio?

function

Usage: (ratio? n)

Returns true if n is a Ratio

Added in Clojure version 1.0
Source

rational?

function

Usage: (rational? n)

Returns true if n is a rational number

Added in Clojure version 1.0
Source

rationalize

function

Usage: (rationalize num)

returns the rational value of num

Added in Clojure version 1.0
Source

re-find

function

Usage: (re-find m)
       (re-find re s)

Returns the next regex match, if any, of string to pattern, using
java.util.regex.Matcher.find().  Uses re-groups to return the
groups.

Added in Clojure version 1.0
Source

re-groups

function

Usage: (re-groups m)

Returns the groups from the most recent match/find. If there are no
nested groups, returns a string of the entire match. If there are
nested groups, returns a vector of the groups, the first element
being the entire match.

Added in Clojure version 1.0
Source

re-matcher

function

Usage: (re-matcher re s)

Returns an instance of java.util.regex.Matcher, for use, e.g. in
re-find.

Added in Clojure version 1.0
Source

re-matches

function

Usage: (re-matches re s)

Returns the match, if any, of string to pattern, using
java.util.regex.Matcher.matches().  Uses re-groups to return the
groups.

Added in Clojure version 1.0
Source

re-pattern

function

Usage: (re-pattern s)

Returns an instance of java.util.regex.Pattern, for use, e.g. in
re-matcher.

Added in Clojure version 1.0
Source

re-seq

function

Usage: (re-seq re s)

Returns a lazy sequence of successive matches of pattern in string,
using java.util.regex.Matcher.find(), each such match processed with
re-groups.

Added in Clojure version 1.0
Source

read

function

Usage: (read)
       (read stream)
       (read stream eof-error? eof-value)
       (read stream eof-error? eof-value recursive?)

Reads the next object from stream, which must be an instance of
java.io.PushbackReader or some derivee.  stream defaults to the
current value of *in*.

Note that read can execute code (controlled by *read-eval*),
and as such should be used only with trusted sources.

For data structure interop use clojure.edn/read

Added in Clojure version 1.0
Source

read-line

function

Usage: (read-line)

Reads the next line from stream that is the current value of *in* .

Added in Clojure version 1.0
Source

read-string

function

Usage: (read-string s)

Reads one object from the string s.

Note that read-string can execute code (controlled by *read-eval*),
and as such should be used only with trusted sources.

For data structure interop use clojure.edn/read-string

Added in Clojure version 1.0
Source

realized?

function

Usage: (realized? x)

Returns true if a value has been produced for a promise, delay, future or lazy sequence.

Added in Clojure version 1.3
Source

record?

function

Usage: (record? x)

Returns true if x is a record

Added in Clojure version 1.6
Source

recur

special form

Usage: (recur exprs*)

Evaluates the exprs in order, then, in parallel, rebinds
the bindings of the recursion point to the values of the exprs.
Execution then jumps back to the recursion point, a loop or fn method.

Please see https://clojure.org/reference/special_forms#recur

Added in Clojure version 1.0

reduce

function

Usage: (reduce f coll)
       (reduce f val coll)

f should be a function of 2 arguments. If val is not supplied,
returns the result of applying f to the first 2 items in coll, then
applying f to that result and the 3rd item, etc. If coll contains no
items, f must accept no arguments as well, and reduce returns the
result of calling f with no arguments.  If coll has only 1 item, it
is returned and f is not called.  If val is supplied, returns the
result of applying f to val and the first item in coll, then
applying f to that result and the 2nd item, etc. If coll contains no
items, returns val and f is not called.

Added in Clojure version 1.0
Source

reduce-kv

function

Usage: (reduce-kv f init coll)

Reduces an associative collection. f should be a function of 3
arguments. Returns the result of applying f to init, the first key
and the first value in coll, then applying f to that result and the
2nd key and value, etc. If coll contains no entries, returns init
and f is not called. Note that reduce-kv is supported on vectors,
where the keys will be the ordinals.

Added in Clojure version 1.4
Source

reduced

function

Usage: (reduced x)

Wraps x in a way such that a reduce will terminate with the value x

Added in Clojure version 1.5
Source

reduced?

function

Usage: (reduced? x)

Returns true if x is the result of a call to reduced

Added in Clojure version 1.5
Source

reductions

function

Usage: (reductions f coll)
       (reductions f init coll)

Returns a lazy seq of the intermediate values of the reduction (as
per reduce) of coll by f, starting with init.

Added in Clojure version 1.2
Source

ref

function

Usage: (ref x)
       (ref x & options)

Creates and returns a Ref with an initial value of x and zero or
more options (in any order):

:meta metadata-map

:validator validate-fn

:min-history (default 0)
:max-history (default 10)

If metadata-map is supplied, it will become the metadata on the
ref. validate-fn must be nil or a side-effect-free fn of one
argument, which will be passed the intended new state on any state
change. If the new state is unacceptable, the validate-fn should
return false or throw an exception. validate-fn will be called on
transaction commit, when all refs have their final values.

Normally refs accumulate history dynamically as needed to deal with
read demands. If you know in advance you will need history you can
set :min-history to ensure it will be available when first needed (instead
of after a read fault). History is limited, and the limit can be set
with :max-history.

Added in Clojure version 1.0
Source

ref-history-count

function

Usage: (ref-history-count ref)

Returns the history count of a ref

Added in Clojure version 1.1
Source

ref-max-history

function

Usage: (ref-max-history ref)
       (ref-max-history ref n)

Gets the max-history of a ref, or sets it and returns the ref

Added in Clojure version 1.1
Source

ref-min-history

function

Usage: (ref-min-history ref)
       (ref-min-history ref n)

Gets the min-history of a ref, or sets it and returns the ref

Added in Clojure version 1.1
Source

ref-set

function

Usage: (ref-set ref val)

Must be called in a transaction. Sets the value of ref.
Returns val.

Added in Clojure version 1.0
Source

refer

function

Usage: (refer ns-sym & filters)

refers to all public vars of ns, subject to filters.
filters can include at most one each of:

:exclude list-of-symbols
:only list-of-symbols
:rename map-of-fromsymbol-tosymbol

For each public interned var in the namespace named by the symbol,
adds a mapping from the name of the var to the var to the current
namespace.  Throws an exception if name is already mapped to
something else in the current namespace. Filters can be used to
select a subset, via inclusion or exclusion, or to provide a mapping
to a symbol different from the var's name, in order to prevent
clashes. Use :use in the ns macro in preference to calling this directly.

Added in Clojure version 1.0
Source

refer-clojure

macro

Usage: (refer-clojure & filters)

Same as (refer 'clojure.core <filters>)

Added in Clojure version 1.0
Source

reify

macro

Usage: (reify & opts+specs)

reify is a macro with the following structure:

(reify options* specs*)
 
 Currently there are no options.

 Each spec consists of the protocol or interface name followed by zero
 or more method bodies:

 protocol-or-interface-or-Object
 (methodName [args+] body)*

 Methods should be supplied for all methods of the desired
 protocol(s) and interface(s). You can also define overrides for
 methods of Object. Note that the first parameter must be supplied to
 correspond to the target object ('this' in Java parlance). Thus
 methods for interfaces will take one more argument than do the
 interface declarations.  Note also that recur calls to the method
 head should *not* pass the target object, it will be supplied
 automatically and can not be substituted.

 The return type can be indicated by a type hint on the method name,
 and arg types can be indicated by a type hint on arg names. If you
 leave out all hints, reify will try to match on same name/arity
 method in the protocol(s)/interface(s) - this is preferred. If you
 supply any hints at all, no inference is done, so all hints (or
 default of Object) must be correct, for both arguments and return
 type. If a method is overloaded in a protocol/interface, multiple
 independent method definitions must be supplied.  If overloaded with
 same arity in an interface you must specify complete hints to
 disambiguate - a missing hint implies Object.

 recur works to method heads The method bodies of reify are lexical
 closures, and can refer to the surrounding local scope:
 
 (str (let [f "foo"] 
      (reify Object 
        (toString [this] f))))
 == "foo"

 (seq (let [f "foo"] 
      (reify clojure.lang.Seqable 
        (seq [this] (seq f)))))
 == (\f \o \o))
 
 reify always implements clojure.lang.IObj and transfers meta
 data of the form to the created object.
 
 (meta ^{:k :v} (reify Object (toString [this] "foo")))
 == {:k :v}

Added in Clojure version 1.2
Source

release-pending-sends

function

Usage: (release-pending-sends)

Normally, actions sent directly or indirectly during another action
are held until the action completes (changes the agent's
state). This function can be used to dispatch any pending sent
actions immediately. This has no impact on actions sent during a
transaction, which are still held until commit. If no action is
occurring, does nothing. Returns the number of actions dispatched.

Added in Clojure version 1.0
Source

rem

function

Usage: (rem num div)

remainder of dividing numerator by denominator.

Added in Clojure version 1.0
Source

remove

function

Usage: (remove pred coll)

Returns a lazy sequence of the items in coll for which
(pred item) returns false. pred must be free of side-effects.

Added in Clojure version 1.0
Source

remove-all-methods

function

Usage: (remove-all-methods multifn)

Removes all of the methods of multimethod.

Added in Clojure version 1.2
Source

remove-method

function

Usage: (remove-method multifn dispatch-val)

Removes the method of multimethod associated with dispatch-value.

Added in Clojure version 1.0
Source

remove-ns

function

Usage: (remove-ns sym)

Removes the namespace named by the symbol. Use with caution.
Cannot be used to remove the clojure namespace.

Added in Clojure version 1.0
Source

remove-watch

function

Usage: (remove-watch reference key)

Removes a watch (set by add-watch) from a reference

Added in Clojure version 1.0
Source

repeat

function

Usage: (repeat x)
       (repeat n x)

Returns a lazy (infinite!, or length n if supplied) sequence of xs.

Added in Clojure version 1.0
Source

repeatedly

function

Usage: (repeatedly f)
       (repeatedly n f)

Takes a function of no args, presumably with side effects, and
returns an infinite (or length n if supplied) lazy sequence of calls
to it

Added in Clojure version 1.0
Source

replace

function

Usage: (replace smap coll)

Given a map of replacement pairs and a vector/collection, returns a
vector/seq with any elements = a key in smap replaced with the
corresponding val in smap

Added in Clojure version 1.0
Source

replicate

function

Usage: (replicate n x)

DEPRECATED: Use 'repeat' instead.
Returns a lazy seq of n xs.

Added in Clojure version 1.0
Deprecated since Clojure version 1.3
Source

require

function

Usage: (require & args)

Loads libs, skipping any that are already loaded. Each argument is
either a libspec that identifies a lib, a prefix list that identifies
multiple libs whose names share a common prefix, or a flag that modifies
how all the identified libs are loaded. Use :require in the ns macro
in preference to calling this directly.

Libs

A 'lib' is a named set of resources in classpath whose contents define a
library of Clojure code. Lib names are symbols and each lib is associated
with a Clojure namespace and a Java package that share its name. A lib's
name also locates its root directory within classpath using Java's
package name to classpath-relative path mapping. All resources in a lib
should be contained in the directory structure under its root directory.
All definitions a lib makes should be in its associated namespace.

'require loads a lib by loading its root resource. The root resource path
is derived from the lib name in the following manner:
Consider a lib named by the symbol 'x.y.z; it has the root directory
<classpath>/x/y/, and its root resource is <classpath>/x/y/z.clj. The root
resource should contain code to create the lib's namespace (usually by using
the ns macro) and load any additional lib resources.

Libspecs

A libspec is a lib name or a vector containing a lib name followed by
options expressed as sequential keywords and arguments.

Recognized options:
:as takes a symbol as its argument and makes that symbol an alias to the
  lib's namespace in the current namespace.
:refer takes a list of symbols to refer from the namespace or the :all
  keyword to bring in all public vars.

Prefix Lists

It's common for Clojure code to depend on several libs whose names have
the same prefix. When specifying libs, prefix lists can be used to reduce
repetition. A prefix list contains the shared prefix followed by libspecs
with the shared prefix removed from the lib names. After removing the
prefix, the names that remain must not contain any periods.

Flags

A flag is a keyword.
Recognized flags: :reload, :reload-all, :verbose
:reload forces loading of all the identified libs even if they are
  already loaded
:reload-all implies :reload and also forces loading of all libs that the
  identified libs directly or indirectly load via require or use
:verbose triggers printing information about each load, alias, and refer

Example:

The following would load the libraries clojure.zip and clojure.set
abbreviated as 's'.

(require '(clojure zip [set :as s]))

Added in Clojure version 1.0
Source

reset!

function

Usage: (reset! atom newval)

Sets the value of atom to newval without regard for the
current value. Returns newval.

Added in Clojure version 1.0
Source

reset-meta!

function

Usage: (reset-meta! iref metadata-map)

Atomically resets the metadata for a namespace/var/ref/agent/atom

Added in Clojure version 1.0
Source

resolve

function

Usage: (resolve sym)
       (resolve env sym)

same as (ns-resolve *ns* symbol) or (ns-resolve *ns* &env symbol)

Added in Clojure version 1.0
Source

rest

function

Usage: (rest coll)

Returns a possibly empty seq of the items after the first. Calls seq on its
argument.

Added in Clojure version 1.0
Source

restart-agent

function

Usage: (restart-agent a new-state & options)

When an agent is failed, changes the agent state to new-state and
then un-fails the agent so that sends are allowed again.  If
a :clear-actions true option is given, any actions queued on the
agent that were being held while it was failed will be discarded,
otherwise those held actions will proceed.  The new-state must pass
the validator if any, or restart will throw an exception and the
agent will remain failed with its old state and error.  Watchers, if
any, will NOT be notified of the new state.  Throws an exception if
the agent is not failed.

Added in Clojure version 1.2
Source

resultset-seq

function

Usage: (resultset-seq rs)

Creates and returns a lazy sequence of structmaps corresponding to
the rows in the java.sql.ResultSet rs

Added in Clojure version 1.0
Source

reverse

function

Usage: (reverse coll)

Returns a seq of the items in coll in reverse order. Not lazy.

Added in Clojure version 1.0
Source

reversible?

function

Usage: (reversible? coll)

Returns true if coll implements Reversible

Added in Clojure version 1.0
Source

rseq

function

Usage: (rseq rev)

Returns, in constant time, a seq of the items in rev (which
can be a vector or sorted-map), in reverse order. If rev is empty returns nil

Added in Clojure version 1.0
Source

rsubseq

function

Usage: (rsubseq sc test key)
       (rsubseq sc start-test start-key end-test end-key)

sc must be a sorted collection, test(s) one of <, <=, > or
>=. Returns a reverse seq of those entries with keys ek for
which (test (.. sc comparator (compare ek key)) 0) is true

Added in Clojure version 1.0
Source

satisfies?

function

Usage: (satisfies? protocol x)

Returns true if x satisfies the protocol

Added in Clojure version 1.2
Source

second

function

Usage: (second x)

Same as (first (next x))

Added in Clojure version 1.0
Source

select-keys

function

Usage: (select-keys map keyseq)

Returns a map containing only those entries in map whose key is in keys

Added in Clojure version 1.0
Source

send

function

Usage: (send a f & args)

Dispatch an action to an agent. Returns the agent immediately.
Subsequently, in a thread from a thread pool, the state of the agent
will be set to the value of:

(apply action-fn state-of-agent args)

Added in Clojure version 1.0
Source

send-off

function

Usage: (send-off a f & args)

Dispatch a potentially blocking action to an agent. Returns the
agent immediately. Subsequently, in a separate thread, the state of
the agent will be set to the value of:

(apply action-fn state-of-agent args)

Added in Clojure version 1.0
Source

send-via

function

Usage: (send-via executor a f & args)

Dispatch an action to an agent. Returns the agent immediately.
Subsequently, in a thread supplied by executor, the state of the agent
will be set to the value of:

(apply action-fn state-of-agent args)

Added in Clojure version 1.5
Source

seq

function

Usage: (seq coll)

Returns a seq on the collection. If the collection is
empty, returns nil.  (seq nil) returns nil. seq also works on
Strings, native Java arrays (of reference types) and any objects
that implement Iterable.

Added in Clojure version 1.0
Source

seq?

function

Usage: (seq? x)

Return true if x implements ISeq

Added in Clojure version 1.0
Source

seque

function

Usage: (seque s)
       (seque n-or-q s)

Creates a queued seq on another (presumably lazy) seq s. The queued
seq will produce a concrete seq in the background, and can get up to
n items ahead of the consumer. n-or-q can be an integer n buffer
size, or an instance of java.util.concurrent BlockingQueue. Note
that reading from a seque can block if the reader gets ahead of the
producer.

Added in Clojure version 1.0
Source

sequence

function

Usage: (sequence coll)

Coerces coll to a (possibly empty) sequence, if it is not already
one. Will not force a lazy seq. (sequence nil) yields ()

Added in Clojure version 1.0
Source

sequential?

function

Usage: (sequential? coll)

Returns true if coll implements Sequential

Added in Clojure version 1.0
Source

set

function

Usage: (set coll)

Returns a set of the distinct elements of coll.

Added in Clojure version 1.0
Source

set!

special form

Usage: (set! var-symbol expr)
       (set! (. instance-expr instanceFieldName-symbol) expr)
       (set! (. Classname-symbol staticFieldName-symbol) expr)

Used to set thread-local-bound vars, Java object instance
fields, and Java class static fields.

Please see https://clojure.org/vars#set

Added in Clojure version 1.0

set-agent-send-executor!

function

Usage: (set-agent-send-executor! executor)

Sets the ExecutorService to be used by send

Added in Clojure version 1.5
Source

set-agent-send-off-executor!

function

Usage: (set-agent-send-off-executor! executor)

Sets the ExecutorService to be used by send-off

Added in Clojure version 1.5
Source

set-error-handler!

function

Usage: (set-error-handler! a handler-fn)

Sets the error-handler of agent a to handler-fn.  If an action
being run by the agent throws an exception or doesn't pass the
validator fn, handler-fn will be called with two arguments: the
agent and the exception.

Added in Clojure version 1.2
Source

set-error-mode!

function

Usage: (set-error-mode! a mode-keyword)

Sets the error-mode of agent a to mode-keyword, which must be
either :fail or :continue.  If an action being run by the agent
throws an exception or doesn't pass the validator fn, an
error-handler may be called (see set-error-handler!), after which,
if the mode is :continue, the agent will continue as if neither the
action that caused the error nor the error itself ever happened.

If the mode is :fail, the agent will become failed and will stop
accepting new 'send' and 'send-off' actions, and any previously
queued actions will be held until a 'restart-agent'.  Deref will
still work, returning the state of the agent before the error.

Added in Clojure version 1.2
Source

set-validator!

function

Usage: (set-validator! iref validator-fn)

Sets the validator-fn for a var/ref/agent/atom. validator-fn must be nil or a
side-effect-free fn of one argument, which will be passed the intended
new state on any state change. If the new state is unacceptable, the
validator-fn should return false or throw an exception. If the current state (root
value if var) is not acceptable to the new validator, an exception
will be thrown and the validator will not be changed.

Added in Clojure version 1.0
Source

set?

function

Usage: (set? x)

Returns true if x implements IPersistentSet

Added in Clojure version 1.0
Source

short

function

Usage: (short x)

Coerce to short

Added in Clojure version 1.0
Source

short-array

function

Usage: (short-array size-or-seq)
       (short-array size init-val-or-seq)

Creates an array of shorts

Added in Clojure version 1.1
Source

shorts

function

Usage: (shorts xs)

Casts to shorts[]

Added in Clojure version 1.1
Source

shuffle

function

Usage: (shuffle coll)

Return a random permutation of coll

Added in Clojure version 1.2
Source

shutdown-agents

function

Usage: (shutdown-agents)

Initiates a shutdown of the thread pools that back the agent
system. Running actions will complete, but no new actions will be
accepted

Added in Clojure version 1.0
Source

slurp

function

Usage: (slurp f & opts)

Opens a reader on f and reads all its contents, returning a string.
See clojure.java.io/reader for a complete list of supported arguments.

Added in Clojure version 1.0
Source

some

function

Usage: (some pred coll)

Returns the first logical true value of (pred x) for any x in coll,
else nil.  One common idiom is to use a set as pred, for example
this will return :fred if :fred is in the sequence, otherwise nil:
(some #{:fred} coll)

Added in Clojure version 1.0
Source

some->

macro

Usage: (some-> expr & forms)

When expr is not nil, threads it into the first form (via ->),
and when that result is not nil, through the next etc

Added in Clojure version 1.5
Source

some->>

macro

Usage: (some->> expr & forms)

When expr is not nil, threads it into the first form (via ->>),
and when that result is not nil, through the next etc

Added in Clojure version 1.5
Source

some-fn

function

Usage: (some-fn p)
       (some-fn p1 p2)
       (some-fn p1 p2 p3)
       (some-fn p1 p2 p3 & ps)

Takes a set of predicates and returns a function f that returns the first logical true value
returned by one of its composing predicates against any of its arguments, else it returns
logical false. Note that f is short-circuiting in that it will stop execution on the first
argument that triggers a logical true result against the original predicates.

Added in Clojure version 1.3
Source

some?

function

Usage: (some? x)

Returns true if x is not nil, false otherwise.

Added in Clojure version 1.6
Source

sort

function

Usage: (sort coll)
       (sort comp coll)

Returns a sorted sequence of the items in coll. If no comparator is
supplied, uses compare.  comparator must implement
java.util.Comparator.  If coll is a Java array, it will be modified.
To avoid this, sort a copy of the array.

Added in Clojure version 1.0
Source

sort-by

function

Usage: (sort-by keyfn coll)
       (sort-by keyfn comp coll)

Returns a sorted sequence of the items in coll, where the sort
order is determined by comparing (keyfn item).  If no comparator is
supplied, uses compare.  comparator must implement
java.util.Comparator.  If coll is a Java array, it will be modified.
To avoid this, sort a copy of the array.

Added in Clojure version 1.0
Source

sorted-map

function

Usage: (sorted-map & keyvals)

keyval => key val
Returns a new sorted map with supplied mappings.  If any keys are
equal, they are handled as if by repeated uses of assoc.

Added in Clojure version 1.0
Source

sorted-map-by

function

Usage: (sorted-map-by comparator & keyvals)

keyval => key val
Returns a new sorted map with supplied mappings, using the supplied
comparator.  If any keys are equal, they are handled as if by
repeated uses of assoc.

Added in Clojure version 1.0
Source

sorted-set

function

Usage: (sorted-set & keys)

Returns a new sorted set with supplied keys.  Any equal keys are
handled as if by repeated uses of conj.

Added in Clojure version 1.0
Source

sorted-set-by

function

Usage: (sorted-set-by comparator & keys)

Returns a new sorted set with supplied keys, using the supplied
comparator.  Any equal keys are handled as if by repeated uses of
conj.

Added in Clojure version 1.1
Source

sorted?

function

Usage: (sorted? coll)

Returns true if coll implements Sorted

Added in Clojure version 1.0
Source

special-symbol?

function

Usage: (special-symbol? s)

Returns true if s names a special form

Added in Clojure version 1.0
Source

spit

function

Usage: (spit f content & options)

Opposite of slurp.  Opens f with writer, writes content, then
closes f. Options passed to clojure.java.io/writer.

Added in Clojure version 1.2
Source

split-at

function

Usage: (split-at n coll)

Returns a vector of [(take n coll) (drop n coll)]

Added in Clojure version 1.0
Source

split-with

function

Usage: (split-with pred coll)

Returns a vector of [(take-while pred coll) (drop-while pred coll)]

Added in Clojure version 1.0
Source

str

function

Usage: (str)
       (str x)
       (str x & ys)

With no args, returns the empty string. With one arg x, returns
x.toString().  (str nil) returns the empty string. With more than
one arg, returns the concatenation of the str values of the args.

Added in Clojure version 1.0
Source

string?

function

Usage: (string? x)

Return true if x is a String

Added in Clojure version 1.0
Source

struct

function

Usage: (struct s & vals)

Returns a new structmap instance with the keys of the
structure-basis. vals must be supplied for basis keys in order -
where values are not supplied they will default to nil.

Added in Clojure version 1.0
Source

struct-map

function

Usage: (struct-map s & inits)

Returns a new structmap instance with the keys of the
structure-basis. keyvals may contain all, some or none of the basis
keys - where values are not supplied they will default to nil.
keyvals can also contain keys not in the basis.

Added in Clojure version 1.0
Source

subs

function

Usage: (subs s start)
       (subs s start end)

Returns the substring of s beginning at start inclusive, and ending
at end (defaults to length of string), exclusive.

Added in Clojure version 1.0
Source

subseq

function

Usage: (subseq sc test key)
       (subseq sc start-test start-key end-test end-key)

sc must be a sorted collection, test(s) one of <, <=, > or
>=. Returns a seq of those entries with keys ek for
which (test (.. sc comparator (compare ek key)) 0) is true

Added in Clojure version 1.0
Source

subvec

function

Usage: (subvec v start)
       (subvec v start end)

Returns a persistent vector of the items in vector from
start (inclusive) to end (exclusive).  If end is not supplied,
defaults to (count vector). This operation is O(1) and very fast, as
the resulting vector shares structure with the original and no
trimming is done.

Added in Clojure version 1.0
Source

supers

function

Usage: (supers class)

Returns the immediate and indirect superclasses and interfaces of c, if any

Added in Clojure version 1.0
Source

swap!

function

Usage: (swap! atom f)
       (swap! atom f x)
       (swap! atom f x y)
       (swap! atom f x y & args)

Atomically swaps the value of atom to be:
(apply f current-value-of-atom args). Note that f may be called
multiple times, and thus should be free of side effects.  Returns
the value that was swapped in.

Added in Clojure version 1.0
Source

symbol

function

Usage: (symbol name)
       (symbol ns name)

Returns a Symbol with the given namespace and name.

Added in Clojure version 1.0
Source

symbol?

function

Usage: (symbol? x)

Return true if x is a Symbol

Added in Clojure version 1.0
Source

sync

macro

Usage: (sync flags-ignored-for-now & body)

transaction-flags => TBD, pass nil for now

Runs the exprs (in an implicit do) in a transaction that encompasses
exprs and any nested calls.  Starts a transaction if none is already
running on this thread. Any uncaught exception will abort the
transaction and flow out of sync. The exprs may be run more than
once, but any effects on Refs will be atomic.

Added in Clojure version 1.0
Source

take

function

Usage: (take n coll)

Returns a lazy sequence of the first n items in coll, or all items if
there are fewer than n.

Added in Clojure version 1.0
Source

take-last

function

Usage: (take-last n coll)

Returns a seq of the last n items in coll.  Depending on the type
of coll may be no better than linear time.  For vectors, see also subvec.

Added in Clojure version 1.1
Source

take-nth

function

Usage: (take-nth n coll)

Returns a lazy seq of every nth item in coll.

Added in Clojure version 1.0
Source

take-while

function

Usage: (take-while pred coll)

Returns a lazy sequence of successive items from coll while
(pred item) returns true. pred must be free of side-effects.

Added in Clojure version 1.0
Source

test

function

Usage: (test v)

test [v] finds fn at key :test in var metadata and calls it,
presuming failure will throw exception

Added in Clojure version 1.0
Source

the-ns

function

Usage: (the-ns x)

If passed a namespace, returns it. Else, when passed a symbol,
returns the namespace named by it, throwing an exception if not
found.

Added in Clojure version 1.0
Source

thread-bound?

function

Usage: (thread-bound? & vars)

Returns true if all of the vars provided as arguments have thread-local bindings.
Implies that set!'ing the provided vars will succeed.  Returns true if no vars are provided.

Added in Clojure version 1.2
Source

throw

special form

Usage: (throw expr)

The expr is evaluated and thrown, therefore it should
yield an instance of some derivee of Throwable.

Please see https://clojure.org/reference/special_forms#throw

Added in Clojure version 1.0

time

macro

Usage: (time expr)

Evaluates expr and prints the time it took.  Returns the value of
expr.

Added in Clojure version 1.0
Source

to-array

function

Usage: (to-array coll)

Returns an array of Objects containing the contents of coll, which
can be any Collection.  Maps to java.util.Collection.toArray().

Added in Clojure version 1.0
Source

to-array-2d

function

Usage: (to-array-2d coll)

Returns a (potentially-ragged) 2-dimensional array of Objects
containing the contents of coll, which can be any Collection of any
Collection.

Added in Clojure version 1.0
Source

trampoline

function

Usage: (trampoline f)
       (trampoline f & args)

trampoline can be used to convert algorithms requiring mutual
recursion without stack consumption. Calls f with supplied args, if
any. If f returns a fn, calls that fn with no arguments, and
continues to repeat, until the return value is not a fn, then
returns that non-fn value. Note that if you want to return a fn as a
final value, you must wrap it in some data structure and unpack it
after trampoline returns.

Added in Clojure version 1.0
Source

transient

function

Usage: (transient coll)

Returns a new, transient version of the collection, in constant time.

Added in Clojure version 1.1
Source

tree-seq

function

Usage: (tree-seq branch? children root)

Returns a lazy sequence of the nodes in a tree, via a depth-first walk.
 branch? must be a fn of one arg that returns true if passed a node
 that can have children (but may not).  children must be a fn of one
 arg that returns a sequence of the children. Will only be called on
 nodes for which branch? returns true. Root is the root node of the
tree.

Added in Clojure version 1.0
Source

true?

function

Usage: (true? x)

Returns true if x is the value true, false otherwise.

Added in Clojure version 1.0
Source

try

special form

Usage: (try expr* catch-clause* finally-clause?)

catch-clause => (catch classname name expr*)
finally-clause => (finally expr*)

Catches and handles Java exceptions.

Please see https://clojure.org/reference/special_forms#try

Added in Clojure version 1.0

type

function

Usage: (type x)

Returns the :type metadata of x, or its Class if none

Added in Clojure version 1.0
Source

unchecked-add

function

Usage: (unchecked-add x y)

Returns the sum of x and y, both long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-add-int

function

Usage: (unchecked-add-int x y)

Returns the sum of x and y, both int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-byte

function

Usage: (unchecked-byte x)

Coerce to byte. Subject to rounding or truncation.

Added in Clojure version 1.3
Source

unchecked-char

function

Usage: (unchecked-char x)

Coerce to char. Subject to rounding or truncation.

Added in Clojure version 1.3
Source

unchecked-dec

function

Usage: (unchecked-dec x)

Returns a number one less than x, a long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-dec-int

function

Usage: (unchecked-dec-int x)

Returns a number one less than x, an int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-divide-int

function

Usage: (unchecked-divide-int x y)

Returns the division of x by y, both int.
Note - uses a primitive operator subject to truncation.

Added in Clojure version 1.0
Source

unchecked-double

function

Usage: (unchecked-double x)

Coerce to double. Subject to rounding.

Added in Clojure version 1.3
Source

unchecked-float

function

Usage: (unchecked-float x)

Coerce to float. Subject to rounding.

Added in Clojure version 1.3
Source

unchecked-inc

function

Usage: (unchecked-inc x)

Returns a number one greater than x, a long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-inc-int

function

Usage: (unchecked-inc-int x)

Returns a number one greater than x, an int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-int

function

Usage: (unchecked-int x)

Coerce to int. Subject to rounding or truncation.

Added in Clojure version 1.3
Source

unchecked-long

function

Usage: (unchecked-long x)

Coerce to long. Subject to rounding or truncation.

Added in Clojure version 1.3
Source

unchecked-multiply

function

Usage: (unchecked-multiply x y)

Returns the product of x and y, both long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-multiply-int

function

Usage: (unchecked-multiply-int x y)

Returns the product of x and y, both int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-negate

function

Usage: (unchecked-negate x)

Returns the negation of x, a long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-negate-int

function

Usage: (unchecked-negate-int x)

Returns the negation of x, an int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-remainder-int

function

Usage: (unchecked-remainder-int x y)

Returns the remainder of division of x by y, both int.
Note - uses a primitive operator subject to truncation.

Added in Clojure version 1.0
Source

unchecked-short

function

Usage: (unchecked-short x)

Coerce to short. Subject to rounding or truncation.

Added in Clojure version 1.3
Source

unchecked-subtract

function

Usage: (unchecked-subtract x y)

Returns the difference of x and y, both long.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

unchecked-subtract-int

function

Usage: (unchecked-subtract-int x y)

Returns the difference of x and y, both int.
Note - uses a primitive operator subject to overflow.

Added in Clojure version 1.0
Source

underive

function

Usage: (underive tag parent)
       (underive h tag parent)

Removes a parent/child relationship between parent and
tag. h must be a hierarchy obtained from make-hierarchy, if not
supplied defaults to, and modifies, the global hierarchy.

Added in Clojure version 1.0
Source

unsigned-bit-shift-right

function

Usage: (unsigned-bit-shift-right x n)

Bitwise shift right, without sign-extension.

Added in Clojure version 1.6
Source

update-in

function

Usage: (update-in m [k & ks] f & args)

'Updates' a value in a nested associative structure, where ks is a
sequence of keys and f is a function that will take the old value
and any supplied args and return the new value, and returns a new
nested structure.  If any levels do not exist, hash-maps will be
created.

Added in Clojure version 1.0
Source

update-proxy

function

Usage: (update-proxy proxy mappings)

Takes a proxy instance and a map of strings (which must
correspond to methods of the proxy superclass/superinterfaces) to
fns (which must take arguments matching the corresponding method,
plus an additional (explicit) first arg corresponding to this, and
updates (via assoc) the proxy's fn map. nil can be passed instead of
a fn, in which case the corresponding method will revert to the
default behavior. Note that this function can be used to update the
behavior of an existing instance without changing its identity.
Returns the proxy.

Added in Clojure version 1.0
Source

use

function

Usage: (use & args)

Like 'require, but also refers to each lib's namespace using
clojure.core/refer. Use :use in the ns macro in preference to calling
this directly.

'use accepts additional options in libspecs: :exclude, :only, :rename.
The arguments and semantics for :exclude, :only, and :rename are the same
as those documented for clojure.core/refer.

Added in Clojure version 1.0
Source

val

function

Usage: (val e)

Returns the value in the map entry.

Added in Clojure version 1.0
Source

vals

function

Usage: (vals map)

Returns a sequence of the map's values, in the same order as (seq map).

Added in Clojure version 1.0
Source

var

special form

Usage: (var symbol)

The symbol must resolve to a var, and the Var object
itself (not its value) is returned. The reader macro #'x
expands to (var x).

Please see https://clojure.org/reference/special_forms#var

Added in Clojure version 1.0

var-get

function

Usage: (var-get x)

Gets the value in the var object

Added in Clojure version 1.0
Source

var-set

function

Usage: (var-set x val)

Sets the value in the var object to val. The var must be
thread-locally bound.

Added in Clojure version 1.0
Source

var?

function

Usage: (var? v)

Returns true if v is of type clojure.lang.Var

Added in Clojure version 1.0
Source

vary-meta

function

Usage: (vary-meta obj f & args)

Returns an object of the same type and value as obj, with
(apply f (meta obj) args) as its metadata.

Added in Clojure version 1.0
Source

vec

function

Usage: (vec coll)

Creates a new vector containing the contents of coll. Java arrays
will be aliased and should not be modified.

Added in Clojure version 1.0
Source

vector

function

Usage: (vector)
       (vector a)
       (vector a b)
       (vector a b c)
       (vector a b c d)
       (vector a b c d & args)

Creates a new vector containing the args.

Added in Clojure version 1.0
Source

vector-of

function

Usage: (vector-of t)
       (vector-of t & elements)

Creates a new vector of a single primitive type t, where t is one
of :int :long :float :double :byte :short :char or :boolean. The
resulting vector complies with the interface of vectors in general,
but stores the values unboxed internally.

Optionally takes one or more elements to populate the vector.

Added in Clojure version 1.2
Source

vector?

function

Usage: (vector? x)

Return true if x implements IPersistentVector

Added in Clojure version 1.0
Source

when

macro

Usage: (when test & body)

Evaluates test. If logical true, evaluates body in an implicit do.

Added in Clojure version 1.0
Source

when-first

macro

Usage: (when-first bindings & body)

bindings => x xs

Roughly the same as (when (seq xs) (let [x (first xs)] body)) but xs is evaluated only once

Added in Clojure version 1.0
Source

when-let

macro

Usage: (when-let bindings & body)

bindings => binding-form test

When test is true, evaluates body with binding-form bound to the value of test

Added in Clojure version 1.0
Source

when-not

macro

Usage: (when-not test & body)

Evaluates test. If logical false, evaluates body in an implicit do.

Added in Clojure version 1.0
Source

when-some

macro

Usage: (when-some bindings & body)

bindings => binding-form test

When test is not nil, evaluates body with binding-form bound to the
value of test

Added in Clojure version 1.6
Source

while

macro

Usage: (while test & body)

Repeatedly executes body while test expression is true. Presumes
some side-effect will cause test to become false/nil. Returns nil

Added in Clojure version 1.0
Source

with-bindings

macro

Usage: (with-bindings binding-map & body)

Takes a map of Var/value pairs. Installs for the given Vars the associated
values as thread-local bindings. The executes body. Pops the installed
bindings after body was evaluated. Returns the value of body.

Added in Clojure version 1.1
Source

with-bindings*

function

Usage: (with-bindings* binding-map f & args)

Takes a map of Var/value pairs. Installs for the given Vars the associated
values as thread-local bindings. Then calls f with the supplied arguments.
Pops the installed bindings after f returned. Returns whatever f returns.

Added in Clojure version 1.1
Source

with-in-str

macro

Usage: (with-in-str s & body)

Evaluates body in a context in which *in* is bound to a fresh
StringReader initialized with the string s.

Added in Clojure version 1.0
Source

with-local-vars

macro

Usage: (with-local-vars name-vals-vec & body)

varbinding=> symbol init-expr

Executes the exprs in a context in which the symbols are bound to
vars with per-thread bindings to the init-exprs.  The symbols refer
to the var objects themselves, and must be accessed with var-get and
var-set

Added in Clojure version 1.0
Source

with-meta

function

Usage: (with-meta obj m)

Returns an object of the same type and value as obj, with
map m as its metadata.

Added in Clojure version 1.0
Source

with-open

macro

Usage: (with-open bindings & body)

bindings => [name init ...]

Evaluates body in a try expression with names bound to the values
of the inits, and a finally clause that calls (.close name) on each
name in reverse order.

Added in Clojure version 1.0
Source

with-out-str

macro

Usage: (with-out-str & body)

Evaluates exprs in a context in which *out* is bound to a fresh
StringWriter.  Returns the string created by any nested printing
calls.

Added in Clojure version 1.0
Source

with-precision

macro

Usage: (with-precision precision & exprs)

Sets the precision and rounding mode to be used for BigDecimal operations.

Usage: (with-precision 10 (/ 1M 3))
or:    (with-precision 10 :rounding HALF_DOWN (/ 1M 3))

The rounding mode is one of CEILING, FLOOR, HALF_UP, HALF_DOWN,
HALF_EVEN, UP, DOWN and UNNECESSARY; it defaults to HALF_UP.

Added in Clojure version 1.0
Source

with-redefs

macro

Usage: (with-redefs bindings & body)

binding => var-symbol temp-value-expr

Temporarily redefines Vars while executing the body.  The
temp-value-exprs will be evaluated and each resulting value will
replace in parallel the root value of its Var.  After the body is
executed, the root values of all the Vars will be set back to their
old values.  These temporary changes will be visible in all threads.
Useful for mocking out functions during testing.

Added in Clojure version 1.3
Source

with-redefs-fn

function

Usage: (with-redefs-fn binding-map func)

Temporarily redefines Vars during a call to func.  Each val of
binding-map will replace the root value of its key which must be
a Var.  After func is called with no args, the root values of all
the Vars will be set back to their old values.  These temporary
changes will be visible in all threads.  Useful for mocking out
functions during testing.

Added in Clojure version 1.3
Source

xml-seq

function

Usage: (xml-seq root)

A tree seq on the xml elements as per xml/parse

Added in Clojure version 1.0
Source

zero?

function

Usage: (zero? x)

Returns true if num is zero, else false

Added in Clojure version 1.0
Source

zipmap

function

Usage: (zipmap keys vals)

Returns a map with the keys mapped to the corresponding vals.

Added in Clojure version 1.0
Source

clojure.core.protocols

Protocols

CollReduce

Protocol

Protocol for collection types that can implement reduce faster than
first/next recursion. Called by clojure.core/reduce. Baseline
implementation defined in terms of Iterable.

Known implementations: clojure.core.reducers.Cat, clojure.lang.ASeq, clojure.lang.LazySeq, clojure.lang.PersistentVector, java.lang.Iterable, nil, Object

coll-reduce

function

Usage: (coll-reduce coll f)
       (coll-reduce coll f val)

Source

IKVReduce

Protocol

Protocol for concrete associative types that can reduce themselves
via a function of key and val faster than first/next recursion over map
entries. Called by clojure.core/reduce-kv, and has same
semantics (just different arg order).

Known implementations: clojure.lang.IPersistentMap, clojure.lang.PersistentArrayMap, clojure.lang.PersistentHashMap, clojure.lang.PersistentTreeMap, clojure.lang.PersistentVector, nil

kv-reduce

function

Usage: (kv-reduce amap f init)

Source

InternalReduce

Protocol

Protocol for concrete seq types that can reduce themselves
faster than first/next recursion. Called by clojure.core/reduce.

Known implementations: clojure.core.VecSeq, clojure.lang.ArraySeq, clojure.lang.ArraySeq$ArraySeq_boolean, clojure.lang.ArraySeq$ArraySeq_byte, clojure.lang.ArraySeq$ArraySeq_char, clojure.lang.ArraySeq$ArraySeq_double, clojure.lang.ArraySeq$ArraySeq_float, clojure.lang.ArraySeq$ArraySeq_int, clojure.lang.ArraySeq$ArraySeq_long, clojure.lang.IChunkedSeq, clojure.lang.StringSeq, nil, Object

internal-reduce

function

Usage: (internal-reduce seq f start)

Source

clojure.core.reducers

A library for reduction and parallel folding. Alpha and subject
to change.  Note that fold and its derivatives require Java 7+ or
Java 6 + jsr166y.jar for fork/join support. See Clojure's pom.xml for the
dependency info.

Types

Cat

type

Fields: [cnt left right]
Protocols: clojure.core.protocols/CollReduce, CollFold
Interfaces: clojure.lang.Counted, clojure.lang.Seqable

Public Variables and Functions

->Cat

function

Usage: (->Cat cnt left right)

Positional factory function for class clojure.core.reducers.Cat.

Source

append!

function

Usage: (append! acc x)

.adds x to acc and returns acc

Added in Clojure version 1.5
Source

cat

function

Usage: (cat)
       (cat ctor)
       (cat left right)

A high-performance combining fn that yields the catenation of the
reduced values. The result is reducible, foldable, seqable and
counted, providing the identity collections are reducible, seqable
and counted. The single argument version will build a combining fn
with the supplied identity constructor. Tests for identity
with (zero? (count x)). See also foldcat.

Added in Clojure version 1.5
Source

drop

function

Usage: (drop n)
       (drop n coll)

Elides the first n values from the reduction of coll.

Added in Clojure version 1.5
Source

filter

function

Usage: (filter pred)
       (filter pred coll)

Retains values in the reduction of coll for which (pred val)
returns logical true. Foldable.

Added in Clojure version 1.5
Source

flatten

function

Usage: (flatten)
       (flatten coll)

Takes any nested combination of sequential things (lists, vectors,
etc.) and returns their contents as a single, flat foldable
collection.

Added in Clojure version 1.5
Source

fold

function

Usage: (fold reducef coll)
       (fold combinef reducef coll)
       (fold n combinef reducef coll)

Reduces a collection using a (potentially parallel) reduce-combine
strategy. The collection is partitioned into groups of approximately
n (default 512), each of which is reduced with reducef (with a seed
value obtained by calling (combinef) with no arguments). The results
of these reductions are then reduced with combinef (default
reducef). combinef must be associative, and, when called with no
arguments, (combinef) must produce its identity element. These
operations may be performed in parallel, but the results will
preserve order.

Added in Clojure version 1.5
Source

foldcat

function

Usage: (foldcat coll)

Equivalent to (fold cat append! coll)

Added in Clojure version 1.5
Source

folder

function

Usage: (folder coll xf)

Given a foldable collection, and a transformation function xf,
returns a foldable collection, where any supplied reducing
fn will be transformed by xf. xf is a function of reducing fn to
reducing fn.

Added in Clojure version 1.5
Source

map

function

Usage: (map f)
       (map f coll)

Applies f to every value in the reduction of coll. Foldable.

Added in Clojure version 1.5
Source

mapcat

function

Usage: (mapcat f)
       (mapcat f coll)

Applies f to every value in the reduction of coll, concatenating the result
colls of (f val). Foldable.

Added in Clojure version 1.5
Source

monoid

function

Usage: (monoid op ctor)

Builds a combining fn out of the supplied operator and identity
constructor. op must be associative and ctor called with no args
must return an identity value for it.

Added in Clojure version 1.5
Source

reduce

function

Usage: (reduce f coll)
       (reduce f init coll)

Like core/reduce except:
When init is not provided, (f) is used.
Maps are reduced with reduce-kv

Source

reducer

function

Usage: (reducer coll xf)

Given a reducible collection, and a transformation function xf,
returns a reducible collection, where any supplied reducing
fn will be transformed by xf. xf is a function of reducing fn to
reducing fn.

Added in Clojure version 1.5
Source

remove

function

Usage: (remove pred)
       (remove pred coll)

Removes values in the reduction of coll for which (pred val)
returns logical true. Foldable.

Added in Clojure version 1.5
Source

take

function

Usage: (take n)
       (take n coll)

Ends the reduction of coll after consuming n values.

Added in Clojure version 1.5
Source

take-while

function

Usage: (take-while pred)
       (take-while pred coll)

Ends the reduction of coll when (pred val) returns logical false.

Added in Clojure version 1.5
Source

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Clojure Core API Reference

Table of Contents

API for clojure.core - Clojure v1.6 (legacy)

Overview

Types

ArrayChunk

Vec

VecNode

VecSeq

Public Variables and Functions

&

*

*'

*1

*2

*3

*agent*

*clojure-version*

*command-line-args*

*compile-files*

*compile-path*

*compiler-options*

*data-readers*

*default-data-reader-fn*

*e

*err*

*file*

*flush-on-newline*

*in*

*ns*

*out*

*print-dup*

*print-length*

*print-level*

*print-meta*

*print-readably*

*read-eval*

*unchecked-math*

*warn-on-reflection*

+

+'

-

-'

->

->>

->ArrayChunk

->Vec

->VecNode

->VecSeq

.

..

/

<

<=

=

==

>

>=

accessor

aclone

add-classpath

add-watch

agent

agent-error

agent-errors

aget

alength

alias

all-ns

alter

alter-meta!

alter-var-root

amap

ancestors

and

apply

areduce

array-map

as->

aset

agent

clojure-version

command-line-args

compile-files

compile-path

compiler-options

data-readers

default-data-reader-fn

err

file

flush-on-newline

in

ns

out

print-dup

print-length

print-level

print-meta

print-readably

read-eval

unchecked-math

warn-on-reflection