Prism.languages.prolog = {
  // Syntax depends on the implementation
  comment: {
    pattern: /\/\*[\s\S]*?\*\/|%.*/,
    greedy: true,
  },
  // Depending on the implementation, strings may allow escaped newlines and quote-escape
  string: {
    pattern: /(["'])(?:\1\1|\\(?:\r\n|[\s\S])|(?!\1)[^\\\r\n])*\1(?!\1)/,
    greedy: true,
  },
  builtin: /\b(?:fx|fy|xf[xy]?|yfx?)\b/,
  // FIXME: Should we list all null-ary predicates (not followed by a parenthesis) like halt, trace, etc.?
  function: /\b[a-z]\w*(?:(?=\()|\/\d+)/,
  number: /\b\d+(?:\.\d*)?/,
  // Custom operators are allowed
  operator: /[:\\=><\-?*@\/;+^|!$.]+|\b(?:is|mod|not|xor)\b/,
  punctuation: /[(){}\[\],]/,
};