grammar.js

module.exports = grammar({
  name: 'racket',

  extras: $ => [ $._comment, /\s+/ ],

  rules: {
    source_file: $ => seq(
      $.lang_line,
      repeat($.datum)
    ),

    lang_line: $ => seq('#lang', $.symbol),

    datum: $ => choice(
      $.number,
      $.symbol,
      $.string,
      $.boolean,
      $.list_or_pair,
      $.quoted_datum
    ),

    boolean:   $ => choice($.true_lit, $.false_lit),
    true_lit:  $ => token(choice("#t", "#T")),
    false_lit: $ => token(choice("#f", "#F")),

    string: $ => seq('"', /[^"]*/, '"'),    // TODO: escaped quotes

    quoted_datum: $ => seq(choice("'", "`"), $.datum),

    number: $ => token(choice(
      /\d+([\./]\d+)?/,
      /#x[0-9A-Fa-f]+/
    )),

    symbol: $ => /[^()\[\]{}",'`;#|\s\\]+/,   // TODO: verbatim symbols with |

    list_or_pair: $ => choice(
      seq("(", repeat(choice($.datum, $.dot)), ")"),
      seq("[", repeat(choice($.datum, $.dot)), "]"),
      seq("{", repeat(choice($.datum, $.dot)), "}"),
    ),

    dot: $ => ".",

    _comment: $ => token(seq(';', /.*/))
  }
});