zprint

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.

See zprint:

• 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.

Use zprint:

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

Get zprint:

• 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

Get something other than the default formatting:

Without learning how to configure 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"

Learn how to alter zprint's formatting behavior:

• How do I change zprint's behavior?

I want to change...

• 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...

Usage

Clojure 1.9, 1.10, 1.10.1:

Leiningen (via Clojars)

Clojurescript:

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.

Clojure 1.8:

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"]

The zprint Reference

• 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

Contributors

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!

Acknowledgements

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!

License

Copyright © 2016-2020 Kim Kinnear

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