zephyr: Zephyr, tree-shaking for the PureScript language

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Tree shaking tool and partial evaluator for PureScript CoreFn AST.

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Versions, 0.1.4, 0.2.0, 0.2.1, 0.3.1, 0.3.2, 0.3.2
Change log ChangeLog.md
Dependencies aeson (>=1.0 && <1.5), ansi-terminal (>=0.7.1 && <0.11), ansi-wl-pprint, async, base (>=4.8 && <5), base-compat (>=0.6.0), boxes (>=0.1.4 && <0.2), bytestring, containers, directory (>=1.2.3), filepath, formatting, Glob (>=0.9 && <0.11), language-javascript (>=0.7.1 && <0.8), mtl (>=2.1.0 && <2.3.0), optparse-applicative (>=0.13.0), purescript (>=0.13.8 && <0.14), safe (>=0.3.9 && <0.4), text, transformers (>=0.3.0 && <0.6), utf8-string (>=1 && <2), zephyr [details]
License MPL-2.0
Copyright (c) 2017-2018 Marcin Szamotulski
Author Marcin Szamotulski <profunctor@pm.me>
Maintainer Marcin Szamotulski <profunctor@pm.me>
Category Development
Home page https://github.com/coot/zephyr#readme
Source repo head: git clone https://github.com/coot/zephyr
Uploaded by coot at 2020-06-28T13:13:50Z



Automatic Flags

use `stack exec zephyr` in tests


test core libs


Use -f <flag> to enable a flag, or -f -<flag> to disable that flag. More info


Maintainer's Corner

For package maintainers and hackage trustees

Readme for zephyr-0.3.2

[back to package description]


Maintainer: coot zephyr

A tree-shaking tool for PureScript. zephyr takes root terms, finds all terms which are required to evaluate them, and generates code just for them. This is done across all dependencies, and can substantially reduce the size of PureScript bundles. zephyr can also evaluate some expressions (an experimental feature).


# compile your project
purs compile -g corefn bower_components/purescript-*/src/**/*.purs src/**/*.purs

# run `zephyr`
zephyr -f Main.main

then you can bundle with purs bundle command:

purs bundle -o app.js -m Main dce-output/**/*.js

You can integrate it with other build tools, see below.

You can specify modules as entry points, which is the same as specifying all exported identifiers.

# include all identifiers from Data.Eq module
zephyr Data.Eq

# as above
zephyr module:Data.Eq

# include Data.Eq.Eq identifier of Data.Eq module
zephyr ident:Data.Eq.Eq

# include 'Data.Eq.eq' identifier
zephyr Data.Eq.eq

zephyr reads corefn json representation from the output directory, removes non transitive dependencies of entry points and generates common js modules (or corefn representation) to dce-output directory.

Evaluation of literal expressions

Zephyr can evaluate some literal expressions.

import Config (isProduction)

a = if isProduction
  then "api/prod/"
  else "api/dev/"

will be transformed to

a = "api/prod/"

whenever isProduction is true. This allows to have different development and production environments while still ship a minified code which only contains production code. You may define isProduction in a module under a src-prod directory and include it when compiling production code with pulp build -I src-prod and to have another copy for your development environment under src-dev where isProduction is set to false.

Integration with build tools

zephyr can be integrated with

Build & Test

cabal build exe:zephyr

To run tests

cabal run zephyr-test


The -f switch is not 100% safe. Upon running, zephyr will remove exports from foreign modules that seems to be not used: are not used in PureScript code and seem not to be used in the foreign module. If you simply assign to exports using JavaScript dot notation then you will be fine, but if you use square notation exports[var] in a dynamic way (i.e. var is a true variable rather than a string literal), then zephyr might remove code that shouldn't be removed.