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matthewleon/language-javascript

Parser for JavaScript, in Haskell

Parser for JavaScript

Build Status

Based (loosely) on language-python

Two Versions

There are currently two versions:

  • 0.5 series : Is a continuation of the 0.5.X.Y series, from the [master]
    (https://github.com/erikd/language-javascript/tree/master) branch of this
    github repository.

  • 0.6 series : This has a vastly different and improved AST which makes if far
    more difficult to build an non-sensical Javascript AST. This code is in the
    new-ast branch of
    this github repository.

How to build

Library:

cabal clean && cabal configure && cabal build

Tests:

cabal clean && cabal configure -fbuildtests && cabal build

Running the tests

./dist/build/runtests/runtests

To debug the grammar

happy -iparse.txt -g -a  -d src/Language/JavaScript/Parser/Grammar5.y

This generates src/Language/JavaScript/Parser/Grammar5.hs, delete this
when done with the debug version

UTF8/Unicode version

Alex 3.0 now supports unicode natively, and has been included as a
dependency in the cabal file.

Note: The generation of the lexical analyser has been separated out,
to remove the install-time dependency on Alex. If any changes
need to be made to the lexer, the Lexer.x source lies in
src-dev, and the runalex.sh script will invoke Alex with the
appropriate directories.

Languages

Haskell68.6%Yacc21.9%Logos8.7%Shell0.5%Makefile0.2%JavaScript0.0%
BSD 3-Clause "New" or "Revised" License
Created December 22, 2017
Updated August 24, 2025