API for clojure.pprint - Clojure v1.5 (stable)

by Tom Faulhaber

Full namespace name: clojure.pprint

Overview

A Pretty Printer for Clojure

clojure.pprint implements a flexible system for printing structured data
in a pleasing, easy-to-understand format. Basic use of the pretty printer is 
simple, just call pprint instead of println. More advanced users can use 
the building blocks provided to create custom output formats. 

Out of the box, pprint supports a simple structured format for basic data 
and a specialized format for Clojure source code. More advanced formats, 
including formats that don't look like Clojure data at all like XML and 
JSON, can be rendered by creating custom dispatch functions. 

In addition to the pprint function, this module contains cl-format, a text 
formatting function which is fully compatible with the format function in 
Common Lisp. Because pretty printing directives are directly integrated with
cl-format, it supports very concise custom dispatch. It also provides
a more powerful alternative to Clojure's standard format function.

See documentation for pprint and cl-format for more information or 
complete documentation on the the clojure web site on github.
Added in Clojure version 1.2

Related documentation:
A Pretty Printer for Clojure

A Common Lisp-compatible Format Function

Public Variables and Functions



*print-base*

dynamic var

    
The base to use for printing integers and rationals.
Added in Clojure version 1.2
Source


*print-miser-width*

dynamic var

    
The column at which to enter miser style. Depending on the dispatch table, 
miser style add newlines in more places to try to keep lines short allowing for further 
levels of nesting.
Added in Clojure version 1.2
Source


*print-pprint-dispatch*

dynamic multimethod
No usage documentation available
The pretty print dispatch function. Use with-pprint-dispatch or set-pprint-dispatch
to modify.
Added in Clojure version 1.2
Source


*print-pretty*

dynamic var

    
Bind to true if you want write to use pretty printing
Added in Clojure version 1.2
Source


*print-radix*

dynamic var

    
Print a radix specifier in front of integers and rationals. If *print-base* is 2, 8, 
or 16, then the radix specifier used is #b, #o, or #x, respectively. Otherwise the 
radix specifier is in the form #XXr where XX is the decimal value of *print-base* 
Added in Clojure version 1.2
Source


*print-right-margin*

dynamic var

    
Pretty printing will try to avoid anything going beyond this column.
Set it to nil to have pprint let the line be arbitrarily long. This will ignore all 
non-mandatory newlines.
Added in Clojure version 1.2
Source


*print-suppress-namespaces*

dynamic var

    
Don't print namespaces with symbols. This is particularly useful when 
pretty printing the results of macro expansions
Added in Clojure version 1.2
Source


cl-format

function
Usage: (cl-format writer format-in & args)
An implementation of a Common Lisp compatible format function. cl-format formats its
arguments to an output stream or string based on the format control string given. It 
supports sophisticated formatting of structured data.

Writer is an instance of java.io.Writer, true to output to *out* or nil to output 
to a string, format-in is the format control string and the remaining arguments 
are the data to be formatted.

The format control string is a string to be output with embedded 'format directives' 
describing how to format the various arguments passed in.

If writer is nil, cl-format returns the formatted result string. Otherwise, cl-format 
returns nil.

For example:
 (let [results [46 38 22]]
        (cl-format true "There ~[are~;is~:;are~]~:* ~d result~:p: ~{~d~^, ~}~%" 
                   (count results) results))

Prints to *out*:
 There are 3 results: 46, 38, 22

Detailed documentation on format control strings is available in the "Common Lisp the 
Language, 2nd edition", Chapter 22 (available online at:
http://www.cs.cmu.edu/afs/cs.cmu.edu/project/ai-repository/ai/html/cltl/clm/node200.html#SECTION002633000000000000000) 
and in the Common Lisp HyperSpec at 
http://www.lispworks.com/documentation/HyperSpec/Body/22_c.htm
Added in Clojure version 1.2
Source


code-dispatch

multimethod
Usage: (code-dispatch object)
The pretty print dispatch function for pretty printing Clojure code.
Added in Clojure version 1.2
Source


formatter

macro
Usage: (formatter format-in)
Makes a function which can directly run format-in. The function is
fn [stream & args] ... and returns nil unless the stream is nil (meaning 
output to a string) in which case it returns the resulting string.

format-in can be either a control string or a previously compiled format.
Added in Clojure version 1.2
Source


formatter-out

macro
Usage: (formatter-out format-in)
Makes a function which can directly run format-in. The function is
fn [& args] ... and returns nil. This version of the formatter macro is
designed to be used with *out* set to an appropriate Writer. In particular,
this is meant to be used as part of a pretty printer dispatch method.

format-in can be either a control string or a previously compiled format.
Added in Clojure version 1.2
Source


fresh-line

function
Usage: (fresh-line)
Make a newline if *out* is not already at the beginning of the line. If *out* is
not a pretty writer (which keeps track of columns), this function always outputs a newline.
Added in Clojure version 1.2
Source


get-pretty-writer

function
Usage: (get-pretty-writer writer)
Returns the java.io.Writer passed in wrapped in a pretty writer proxy, unless it's 
already a pretty writer. Generally, it is unneccesary to call this function, since pprint,
write, and cl-format all call it if they need to. However if you want the state to be 
preserved across calls, you will want to wrap them with this. 

For example, when you want to generate column-aware output with multiple calls to cl-format, 
do it like in this example:

    (defn print-table [aseq column-width]
      (binding [*out* (get-pretty-writer *out*)]
        (doseq [row aseq]
          (doseq [col row]
            (cl-format true "~4D~7,vT" col column-width))
          (prn))))

Now when you run:

    user> (print-table (map #(vector % (* % %) (* % % %)) (range 1 11)) 8)

It prints a table of squares and cubes for the numbers from 1 to 10:

       1      1       1    
       2      4       8    
       3      9      27    
       4     16      64    
       5     25     125    
       6     36     216    
       7     49     343    
       8     64     512    
       9     81     729    
      10    100    1000
Added in Clojure version 1.2
Source


pp

macro
Usage: (pp)
A convenience macro that pretty prints the last thing output. This is
exactly equivalent to (pprint *1).
Added in Clojure version 1.2
Source


pprint

function
Usage: (pprint object)
       (pprint object writer)
Pretty print object to the optional output writer. If the writer is not provided, 
print the object to the currently bound value of *out*.
Added in Clojure version 1.2
Source


pprint-indent

function
Usage: (pprint-indent relative-to n)
Create an indent at this point in the pretty printing stream. This defines how 
following lines are indented. relative-to can be either :block or :current depending 
whether the indent should be computed relative to the start of the logical block or
the current column position. n is an offset. 

This function is intended for use when writing custom dispatch functions.

Output is sent to *out* which must be a pretty printing writer.
Added in Clojure version 1.2
Source


pprint-logical-block

macro
Usage: (pprint-logical-block options* body)
Execute the body as a pretty printing logical block with output to *out* which 
must be a pretty printing writer. When used from pprint or cl-format, this can be 
assumed. 

This function is intended for use when writing custom dispatch functions.

Before the body, the caller can optionally specify options: :prefix, :per-line-prefix, 
and :suffix.
Added in Clojure version 1.2
Source


pprint-newline

function
Usage: (pprint-newline kind)
Print a conditional newline to a pretty printing stream. kind specifies if the 
newline is :linear, :miser, :fill, or :mandatory. 

This function is intended for use when writing custom dispatch functions.

Output is sent to *out* which must be a pretty printing writer.
Added in Clojure version 1.2
Source


pprint-tab

function
Usage: (pprint-tab kind colnum colinc)
Tab at this point in the pretty printing stream. kind specifies whether the tab
is :line, :section, :line-relative, or :section-relative. 

Colnum and colinc specify the target column and the increment to move the target
forward if the output is already past the original target.

This function is intended for use when writing custom dispatch functions.

Output is sent to *out* which must be a pretty printing writer.

THIS FUNCTION IS NOT YET IMPLEMENTED.
Added in Clojure version 1.2
Source


print-length-loop

macro
Usage: (print-length-loop bindings & body)
A version of loop that iterates at most *print-length* times. This is designed 
for use in pretty-printer dispatch functions.
Added in Clojure version 1.3
Source


print-table

function
Usage: (print-table ks rows)
       (print-table rows)
Alpha - subject to change.
Prints a collection of maps in a textual table. Prints table headings
ks, and then a line of output for each row, corresponding to the keys
in ks. If ks are not specified, use the keys of the first item in rows.
Added in Clojure version 1.3
Source


set-pprint-dispatch

function
Usage: (set-pprint-dispatch function)
Set the pretty print dispatch function to a function matching (fn [obj] ...)
where obj is the object to pretty print. That function will be called with *out* set
to a pretty printing writer to which it should do its printing.

For example functions, see simple-dispatch and code-dispatch in 
clojure.pprint.dispatch.clj.
Added in Clojure version 1.2
Source


simple-dispatch

multimethod
Usage: (simple-dispatch object)
The pretty print dispatch function for simple data structure format.
Added in Clojure version 1.2
Source


with-pprint-dispatch

macro
Usage: (with-pprint-dispatch function & body)
Execute body with the pretty print dispatch function bound to function.
Added in Clojure version 1.2
Source


write

function
Usage: (write object & kw-args)
Write an object subject to the current bindings of the printer control variables.
Use the kw-args argument to override individual variables for this call (and any 
recursive calls). Returns the string result if :stream is nil or nil otherwise.

The following keyword arguments can be passed with values:
  Keyword              Meaning                              Default value
  :stream              Writer for output or nil             true (indicates *out*)
  :base                Base to use for writing rationals    Current value of *print-base*
  :circle*             If true, mark circular structures    Current value of *print-circle*
  :length              Maximum elements to show in sublists Current value of *print-length*
  :level               Maximum depth                        Current value of *print-level*
  :lines*              Maximum lines of output              Current value of *print-lines*
  :miser-width         Width to enter miser mode            Current value of *print-miser-width*
  :dispatch            The pretty print dispatch function   Current value of *print-pprint-dispatch*
  :pretty              If true, do pretty printing          Current value of *print-pretty*
  :radix               If true, prepend a radix specifier   Current value of *print-radix*
  :readably*           If true, print readably              Current value of *print-readably*
  :right-margin        The column for the right margin      Current value of *print-right-margin*
  :suppress-namespaces If true, no namespaces in symbols    Current value of *print-suppress-namespaces*

  * = not yet supported
Added in Clojure version 1.2
Source


write-out

function
Usage: (write-out object)
Write an object to *out* subject to the current bindings of the printer control 
variables. Use the kw-args argument to override individual variables for this call (and 
any recursive calls).

*out* must be a PrettyWriter if pretty printing is enabled. This is the responsibility
of the caller.

This method is primarily intended for use by pretty print dispatch functions that 
already know that the pretty printer will have set up their environment appropriately.
Normal library clients should use the standard "write" interface. 
Added in Clojure version 1.2
Source
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