api.js

/**
 * Takes a list of elements and functions (`vfn` and `kfn`) for transforming the string.
 * The resulting elements from applying each function will become the `key` and `value` in
 * the resulting object.
 *
 * For example:
 *
 * ```js
 * const tokens = ['foo-bar', 'top-kek'];
 * const Obj = foldTokens_(tokens, R.split('-'), R.toUpper);
 *
 * // => { 'FOO-BAR': ['foo', 'bar'], 'TOP-KEK': ['top', 'kek'] }
 * ```
 *
 * Useful for re-mapping token strings into some desired form, e.g. turning pascal case
 * string tokens into camelCase.
 *
 * `vfn` and `kfn` will fall back to using Sanctuary's `id` function if not supplied.
 *
 * @sig Foldable a => a -> (a -> b) -> (a -> String) -> StrMap b
 */
const foldTokens_ =
  def('foldTokens_',
      { a: [Z.Foldable] },
      [a, $.Function([a, b]), $.Function([a, $.String]), $.StrMap(b)],
      (xs, vfn, kfn) => L.foldl((o, k) => L.set(kfn(k), vfn(k), o), {}, L.elems, xs));