zprint is a library and command line tool providing a variety of pretty printing capabilities for both Clojure code and Clojure/EDN structures. It can meet almost anyone's needs. As such, it supports a number of major source code formattng approaches.

• classic zprint -- ignores whitespace in function definitions and formats code with a variety of heuristics to look as good as hand-formatted code (see examples)
• respect blank lines -- similar to classic zprint, but blank lines inside of function defintions are retained, while code is otherwise formatted to look beautiful (see examples)
• indent only -- very different from classic zprint -- no code ever changes lines, it is only correctly indented on whatever line it was already on (see examples)

In addition, zprint is very handy to use at the REPL.

• to format whole files
• while using an editor
• at the REPL
• from inside a Clojure(script) program

• a standalone binary for macOS starts in <50 ms
• a standalone binary for Linux starts in <50 ms
• an uberjar for any Java enabled platform starts in several seconds
• an accelerated uberjar for any Java enabled platform starts in about 1s
• a library to use at the REPL
• other ways to access zprint

Maybe one of the existing "styles" will meet your needs. All you have to do is put {:style ...} on the command line or as the third argument to a zprint call. For example, {:style :community} or {:style :respect-bl}.

Some commonly used styles:

• Format using "community" standards
• Respect blank lines
• Indent Only
• Respect all newlines
• Detect and format hiccup vectors
• Justify all pairs
• Backtranslate quote, deref, var, unquote in structures
• Detect keywords in vectors, if found respect newlines
• Sort dependencies in project.clj
• Support "How to ns"

• How do I change zprint's behavior?

• how user defined functions are formatted
• the indentation in lists
• the configuration to track the "community" standard
• how blank lines in source are handled
• how map keys are formatted
• the colors used for formatting source
• how the second element of a pair is indented
• how comments are handled
• anything else...

Leiningen (via Clojars)

zprint has been tested in each of the following environments:

• Clojurescript 1.10.520
  • figwheel 0.5.19
  • shadow-cljs 2.8.62
• lumo 1.10.1
• planck 2.24.0

It requires tools.reader at least 1.0.5, which all of the environments above contain.

The last zprint release built with Clojure 1.8 was [zprint "0.4.15"].

In addition to the zprint dependency, you also need to include the following library when using Clojure 1.8:

[clojure-future-spec "1.9.0-alpha17"]

• Entire reference document
• What does zprint do?
• Features
• The zprint API
• Configuration
  • Configuration uses an options map
  • Where to put an options map
  • Simplified Configuration -- using :style
    • Respect blank lines
    • Indent Only
    • Format using "community" standards
    • Respect all newlines
    • Detect and format hiccup vectors
    • Justify all pairs
    • Backtranslate quote, deref, var, unquote in structures
    • Detect keywords in vectors, if found respect newlines
    • Sort dependencies in project.clj
    • Support "How to ns"
    • Add newlines between pairs in let binding vectors
    • Add newlines between cond, assoc pairs
    • Add newlines between extend clauses
    • Add newlines between map pairs
  • Options map format
    • Option Validation
    • What is Configurable
  • Generalized Capabilities
  • Syntax Coloring
  • Function Classification for Pretty Printing
    • Changing or Adding Function Classifications
    • Replacing functions with reader-macros
    • Controlling single and multi-line output
    • A note about two-up printing
    • A note on justifying two-up printing
  • Formatting large or deep collections
  • Widely Used Configuration Parameters
  • Configurable Elements
    • :agent
    • :array
    • :atom
    • :binding
    • :comment
    • :delay
    • :extend
    • :fn
    • :future
    • :list
    • :map
    • :object
    • :pair
    • :pair-fn
    • :promise
    • :reader-cond
    • :record
    • :set
    • :spec
    • :style
    • :style-map
    • :tab
    • :vector
    • :vector-fn

A number of folks have contributed to zprint, not all of whom show up on GitHub because I have integrated the code or suggestions manually. Thanks for all of the great contributions!

• --url and --url-only: @coltnz
• Suggestion/encouragement to implement :respect-bl: @griffis
• :option-fn and :fn-format for enhanced vector formatting: @milankinen
• Fixed missing require in spec.cljc: @Quezion
• Corrected readme: @griffis
• Fixed nested reader conditional: @rgould1
• Clarified and added useful example for clj usage: @bherrmann7
• Suggested fix for international chars and graalVM native image: @huahaiy

Thanks to everyone who has contributed fixes as well as everyone who has reported an issue. I really appreciate all of the help making zprint better for everybody!

At the core of zprint is the rewrite-clj library by Yannick Scherer, which will parse Clojure source into a zipper. This is a great library! I would not have attempted zprint if rewrite-clj didn't exist to build upon. The Clojurescript port relies on Magnus Rundberget's port of rewrite-clj to Clojurescript, rewrite-cljs. It too worked with no issues when porting to Clojurescript!

Copyright © 2016-2020 Kim Kinnear

Distributed under the MIT License. See the file LICENSE for details.