text: module.exports = function(hljs) {
    var COMMENT_MODES = [
      hljs.COMMENT('--', '$'),
      hljs.COMMENT(
        '{-',
        '-}',
        {
          contains: ['self']
        }
      )
    ];
  
    var CONSTRUCTOR = {
      className: 'type',
      begin: '\\b[A-Z][\\w\']*', // TODO: other constructors (build-in, infix).
      relevance: 0
    };
  
    var LIST = {
      className: 'container',
      begin: '\\(', end: '\\)',
      illegal: '"',
      contains: [
        {className: 'type', begin: '\\b[A-Z][\\w]*(\\((\\.\\.|,|\\w+)\\))?'},
        hljs.inherit(hljs.TITLE_MODE, {begin: '[_a-z][\\w\']*'})
      ].concat(COMMENT_MODES)
    };
  
    var RECORD = {
      className: 'container',
      begin: '{', end: '}',
      contains: LIST.contains
    };
  
    return {
      keywords:
        'let in if then else case of where module import exposing ' +
        'type alias as infix infixl infixr port',
      contains: [
  
        // Top-level constructions.
  
        {
          className: 'module',
          begin: '\\bmodule\\b', end: 'where',
          keywords: 'module where',
          contains: [LIST].concat(COMMENT_MODES),
          illegal: '\\W\\.|;'
        },
        {
          className: 'import',
          begin: '\\bimport\\b', end: '$',
          keywords: 'import|0 as exposing',
          contains: [LIST].concat(COMMENT_MODES),
          illegal: '\\W\\.|;'
        },
        {
          className: 'typedef',
          begin: '\\btype\\b', end: '$',
          keywords: 'type alias',
          contains: [CONSTRUCTOR, LIST, RECORD].concat(COMMENT_MODES)
        },
        {
          className: 'infix',
          beginKeywords: 'infix infixl infixr', end: '$',
          contains: [hljs.C_NUMBER_MODE].concat(COMMENT_MODES)
        },
        {
          className: 'foreign',
          begin: '\\bport\\b', end: '$',
          keywords: 'port',
          contains: COMMENT_MODES
        },
  
        // Literals and names.
  
        // TODO: characters.
        hljs.QUOTE_STRING_MODE,
        hljs.C_NUMBER_MODE,
        CONSTRUCTOR,
        hljs.inherit(hljs.TITLE_MODE, {begin: '^[_a-z][\\w\']*'}),
  
        {begin: '->|<-'} // No markup, relevance booster
      ].concat(COMMENT_MODES)
    };
  };