function tokensToFunction (tokens) {
  // Compile all the tokens into regexps.
  var matches = new Array(tokens.length);

  // Compile all the patterns before compilation.
  for (var i = 0; i < tokens.length; i++) {
    if (typeof tokens[i] === 'object') {
      matches[i] = new RegExp('^(?:' + tokens[i].pattern + ')$');
    }
  }

  return function (obj, opts) {
    var path = '';
    var data = obj || {};
    var options = opts || {};
    var encode = options.pretty ? encodeURIComponentPretty : encodeURIComponent;

    for (var i = 0; i < tokens.length; i++) {
      var token = tokens[i];

      if (typeof token === 'string') {
        path += token;

        continue
      }

      var value = data[token.name];
      var segment;

      if (value == null) {
        if (token.optional) {
          // Prepend partial segment prefixes.
          if (token.partial) {
            path += token.prefix;
          }

          continue
        } else {
          throw new TypeError('Expected "' + token.name + '" to be defined')
        }
      }

      if (isarray(value)) {
        if (!token.repeat) {
          throw new TypeError('Expected "' + token.name + '" to not repeat, but received `' + JSON.stringify(value) + '`')
        }

        if (value.length === 0) {
          if (token.optional) {
            continue
          } else {
            throw new TypeError('Expected "' + token.name + '" to not be empty')
          }
        }

        for (var j = 0; j < value.length; j++) {
          segment = encode(value[j]);

          if (!matches[i].test(segment)) {
            throw new TypeError('Expected all "' + token.name + '" to match "' + token.pattern + '", but received `' + JSON.stringify(segment) + '`')
          }

          path += (j === 0 ? token.prefix : token.delimiter) + segment;
        }

        continue
      }

      segment = token.asterisk ? encodeAsterisk(value) : encode(value);

      if (!matches[i].test(segment)) {
        throw new TypeError('Expected "' + token.name + '" to match "' + token.pattern + '", but received "' + segment + '"')
      }

      path += token.prefix + segment;
    }

    return path
  }
}
Expose a method for transforming tokens into the path function.