ParserLang

ParserLang is parser combinator library. It lets you make parsers by combining other parsers.

Its primary superpower is the ability to define parsers declaratively with template literals:

import { lang } from 'parser-lang';

let { calc } = lang`
  num = /[0-9]+/ > ${ch => parseInt(ch, 10)};

  addExpr = num '+' multExpr > ${([left, op, right]) => left + right}
          | num ;

  multExpr = addExpr '*' multExpr > ${([left, op, right]) => left * right}
           | addExpr ;
  
  calc = multExpr ;
`;

calc.tryParse('1+1*2');
// 3

It's monadic and stuff but don't get too hung up on that. It tries to be very friendly.

Installing

npm install parser-lang

Documentation

• Tutorial
• API Reference

Related Projects/Papers

• Parsimmon - a JavaScript parser combinator library. ParserLang is heavily inspired by Parsimmon. Parsimmon is more coupled to parsing strings (ParserLang uses the Context protocol to support a variety of input types) but also supports a wider variety of JavaScript runtimes.
• Parsec - a Haskell parser combinator library
• Monadic Parser Combinators - one of the seminal papers describing parser combinators