API Overview - Clojure v1.1 (legacy)

Important Clojure resources


Detailed API documentation
Fundamental library of the Clojure language
Contents: & * *1 *2 *3 *agent* *clojure-version* *command-line-args* *compile-files* *compile-path* *e *err* *file* *flush-on-newline* *in* *ns* *out* *print-dup* *print-length* *print-level* *print-meta* *print-readably* *read-eval* *warn-on-reflection* + - -> ->> . .. / < <= = == > >= accessor aclone add-classpath add-watch agent agent-errors aget alength alias all-ns alter alter-meta! alter-var-root amap ancestors and apply areduce array-map aset aset-boolean aset-byte aset-char aset-double aset-float aset-int aset-long aset-short assert assoc assoc! assoc-in associative? atom await await-for bases bean bigdec bigint binding bit-and bit-and-not bit-clear bit-flip bit-not bit-or bit-set bit-shift-left bit-shift-right bit-test bit-xor boolean boolean-array booleans bound-fn bound-fn* butlast byte byte-array bytes cast catch char char-array char-escape-string char-name-string char? chars class class? clear-agent-errors clojure-version coll? comment commute comp comparator compare compare-and-set! compile complement concat cond condp conj conj! cons constantly construct-proxy contains? count counted? create-ns create-struct cycle dec decimal? declare def definline defmacro defmethod defmulti defn defn- defonce defstruct delay delay? deliver deref derive descendants disj disj! dissoc dissoc! distinct distinct? do doall doc dorun doseq dosync dotimes doto double double-array doubles drop drop-last drop-while empty empty? ensure enumeration-seq eval even? every? false? ffirst file-seq filter finally find find-doc find-ns find-var first float float-array float? floats flush fn fn? fnext for force format future future-call future-cancel future-cancelled? future-done? future? gen-class gen-interface gensym get get-in get-method get-proxy-class get-thread-bindings get-validator hash hash-map hash-set identical? identity if if-let if-not ifn? import in-ns inc init-proxy instance? int int-array integer? interleave intern interpose into into-array ints io! isa? iterate iterator-seq juxt key keys keyword keyword? last lazy-cat lazy-seq let letfn line-seq list list* list? load load-file load-reader load-string loaded-libs locking long long-array longs loop macroexpand macroexpand-1 make-array make-hierarchy map map? mapcat max max-key memfn memoize merge merge-with meta methods min min-key mod monitor-enter monitor-exit name namespace neg? new newline next nfirst nil? nnext not not-any? not-empty not-every? not= ns ns-aliases ns-imports ns-interns ns-map ns-name ns-publics ns-refers ns-resolve ns-unalias ns-unmap nth nthnext num number? odd? or parents partial partition pcalls peek persistent! pmap pop pop! pop-thread-bindings pos? pr pr-str prefer-method prefers print print-namespace-doc print-str printf println println-str prn prn-str promise proxy proxy-mappings proxy-super push-thread-bindings pvalues quot quote rand rand-int range ratio? rationalize re-find re-groups re-matcher re-matches re-pattern re-seq read read-line read-string recur reduce ref ref-history-count ref-max-history ref-min-history ref-set refer refer-clojure release-pending-sends rem remove remove-method remove-ns remove-watch repeat repeatedly replace replicate require reset! reset-meta! resolve rest resultset-seq reverse reversible? rseq rsubseq second select-keys send send-off seq seq? seque sequence sequential? set set! set-validator! set? short short-array shorts shutdown-agents slurp some sort sort-by sorted-map sorted-map-by sorted-set sorted-set-by sorted? special-form-anchor special-symbol? split-at split-with str stream? string? struct struct-map subs subseq subvec supers swap! symbol symbol? sync syntax-symbol-anchor take take-last take-nth take-while test the-ns throw time to-array to-array-2d trampoline transient tree-seq true? try type unchecked-add unchecked-dec unchecked-divide unchecked-inc unchecked-multiply unchecked-negate unchecked-remainder unchecked-subtract underive update-in update-proxy use val vals var var-get var-set var? vary-meta vec vector vector? when when-first when-let when-not while with-bindings with-bindings* with-in-str with-local-vars with-meta with-open with-out-str with-precision xml-seq zero? zipmap


by Rich Hickey
Detailed API documentation
Graphical object inspector for Clojure data structures.
Contents: inspect inspect-table inspect-tree


Detailed API documentation

  load-script main repl repl-caught repl-exception repl-prompt repl-read skip-if-eol skip-whitespace with-bindings 


by Rich Hickey
Detailed API documentation
Set operations such as union/intersection.
Contents: difference index intersection join map-invert project rename rename-keys select union


by Stuart Sierra
Detailed API documentation
Print stack traces oriented towards Clojure, not Java.
Contents: e print-cause-trace print-stack-trace print-throwable print-trace-element root-cause


by Stuart Sierra
Detailed API documentation
Macros that expand to repeated copies of a template expression.
Contents: apply-template do-template


by Stuart Sierra, with contributions and suggestions by Chas Emerick, Allen Rohner, and Stuart Halloway
Detailed API documentation
A unit testing framework.


The core of the library is the "is" macro, which lets you make
assertions of any arbitrary expression:

(is (= 4 (+ 2 2)))
(is (instance? Integer 256))
(is (.startsWith "abcde" "ab"))

You can type an "is" expression directly at the REPL, which will
print a message if it fails.

    user> (is (= 5 (+ 2 2)))

    FAIL in  (:1)
    expected: (= 5 (+ 2 2))
      actual: (not (= 5 4))

The "expected:" line shows you the original expression, and the
"actual:" shows you what actually happened.  In this case, it
shows that (+ 2 2) returned 4, which is not = to 5.  Finally, the
"false" on the last line is the value returned from the
expression.  The "is" macro always returns the result of the
inner expression.

There are two special assertions for testing exceptions.  The
"(is (thrown? c ...))" form tests if an exception of class c is

(is (thrown? ArithmeticException (/ 1 0))) 

"(is (thrown-with-msg? c re ...))" does the same thing and also
tests that the message on the exception matches the regular
expression re:

(is (thrown-with-msg? ArithmeticException #"Divide by zero"
                      (/ 1 0)))


"is" takes an optional second argument, a string describing the
assertion.  This message will be included in the error report.

(is (= 5 (+ 2 2)) "Crazy arithmetic")

In addition, you can document groups of assertions with the
"testing" macro, which takes a string followed by any number of
assertions.  The string will be included in failure reports.
Calls to "testing" may be nested, and all of the strings will be
joined together with spaces in the final report, in a style
similar to RSpec <http://rspec.info/>

(testing "Arithmetic"
  (testing "with positive integers"
    (is (= 4 (+ 2 2)))
    (is (= 7 (+ 3 4))))
  (testing "with negative integers"
    (is (= -4 (+ -2 -2)))
    (is (= -1 (+ 3 -4)))))

Note that, unlike RSpec, the "testing" macro may only be used
INSIDE a "deftest" or "with-test" form (see below).


There are two ways to define tests.  The "with-test" macro takes
a defn or def form as its first argument, followed by any number
of assertions.  The tests will be stored as metadata on the

    (defn my-function [x y]
      (+ x y))
  (is (= 4 (my-function 2 2)))
  (is (= 7 (my-function 3 4))))

As of Clojure SVN rev. 1221, this does not work with defmacro.
See http://code.google.com/p/clojure/issues/detail?id=51

The other way lets you define tests separately from the rest of
your code, even in a different namespace:

(deftest addition
  (is (= 4 (+ 2 2)))
  (is (= 7 (+ 3 4))))

(deftest subtraction
  (is (= 1 (- 4 3)))
  (is (= 3 (- 7 4))))

This creates functions named "addition" and "subtraction", which
can be called like any other function.  Therefore, tests can be
grouped and composed, in a style similar to the test framework in
Peter Seibel's "Practical Common Lisp"

(deftest arithmetic

The names of the nested tests will be joined in a list, like
"(arithmetic addition)", in failure reports.  You can use nested
tests to set up a context shared by several tests.


Run tests with the function "(run-tests namespaces...)":

(run-tests 'your.namespace 'some.other.namespace)

If you don't specify any namespaces, the current namespace is
used.  To run all tests in all namespaces, use "(run-all-tests)".

By default, these functions will search for all tests defined in
a namespace and run them in an undefined order.  However, if you
are composing tests, as in the "arithmetic" example above, you
probably do not want the "addition" and "subtraction" tests run
separately.  In that case, you must define a special function
named "test-ns-hook" that runs your tests in the correct order:

(defn test-ns-hook []


You can bind the variable "*load-tests*" to false when loading or
compiling code in production.  This will prevent any tests from
being created by "with-test" or "deftest".


Fixtures allow you to run code before and after tests, to set up
the context in which tests should be run.

A fixture is just a function that calls another function passed as
an argument.  It looks like this:

(defn my-fixture [f]
   Perform setup, establish bindings, whatever.
  (f)  Then call the function we were passed.
   Tear-down / clean-up code here.

Fixtures are attached to namespaces in one of two ways.  "each"
fixtures are run repeatedly, once for each test function created
with "deftest" or "with-test".  "each" fixtures are useful for
establishing a consistent before/after state for each test, like
clearing out database tables.

"each" fixtures can be attached to the current namespace like this:
(use-fixtures :each fixture1 fixture2 ...)
The fixture1, fixture2 are just functions like the example above.
They can also be anonymous functions, like this:
(use-fixtures :each (fn [f] setup... (f) cleanup...))

The other kind of fixture, a "once" fixture, is only run once,
around ALL the tests in the namespace.  "once" fixtures are useful
for tasks that only need to be performed once, like establishing
database connections, or for time-consuming tasks.

Attach "once" fixtures to the current namespace like this:
(use-fixtures :once fixture1 fixture2 ...)


All the test reporting functions write to the var *test-out*.  By
default, this is the same as *out*, but you can rebind it to any
PrintWriter.  For example, it could be a file opened with


You can extend the behavior of the "is" macro by defining new
methods for the "assert-expr" multimethod.  These methods are
called during expansion of the "is" macro, so they should return
quoted forms to be evaluated.

You can plug in your own test-reporting framework by rebinding
the "report" function: (report event)

The 'event' argument is a map.  It will always have a :type key,
whose value will be a keyword signaling the type of event being
reported.  Standard events with :type value of :pass, :fail, and
:error are called when an assertion passes, fails, and throws an
exception, respectively.  In that case, the event will also have
the following keys:

  :expected   The form that was expected to be true
  :actual     A form representing what actually occurred
  :message    The string message given as an argument to 'is'

The "testing" strings will be a list in "*testing-contexts*", and
the vars being tested will be a list in "*testing-vars*".

Your "report" function should wrap any printing calls in the
"with-test-out" macro, which rebinds *out* to the current value
of *test-out*.

For additional event types, see the examples in the code.
Contents: *load-tests* *stack-trace-depth* are assert-any assert-predicate compose-fixtures deftest deftest- file-position function? get-possibly-unbound-var inc-report-counter is join-fixtures report run-all-tests run-tests set-test successful? test-all-vars test-ns test-var testing testing-contexts-str testing-vars-str try-expr use-fixtures with-test with-test-out

Variables and functions in clojure.test.junit: with-junit-output

Variables and functions in clojure.test.tap: print-tap-diagnostic print-tap-fail print-tap-pass print-tap-plan with-tap-output


by Stuart Sierra
Detailed API documentation
This file defines a generic tree walker for Clojure data
structures.  It takes any data structure (list, vector, map, set,
seq), calls a function on every element, and uses the return value
of the function in place of the original.  This makes it fairly
easy to write recursive search-and-replace functions, as shown in
the examples.

Note: "walk" supports all Clojure data structures EXCEPT maps
created with sorted-map-by.  There is no (obvious) way to retrieve
the sorting function.
Contents: keywordize-keys macroexpand-all postwalk postwalk-demo postwalk-replace prewalk prewalk-demo prewalk-replace stringify-keys walk


by Rich Hickey
Detailed API documentation
XML reading/writing.
Contents: parse


by Rich Hickey
Detailed API documentation
Functional hierarchical zipper, with navigation, editing, 
and enumeration.  See Huet
Contents: append-child branch? children down edit end? insert-child insert-left insert-right left leftmost lefts make-node next node path prev remove replace right rightmost rights root seq-zip up vector-zip xml-zip zipper
Logo & site design by Tom Hickey.
Clojure auto-documentation system by Tom Faulhaber.