mezzanine/lib/data-types/maybe.js

Fantasy land union types with pattern matching

'use strict';Object.defineProperty(exports, "__esModule", { value: true });

var _ramda = require('ramda');

var _union = require('../union');var _union2 = _interopRequireDefault(_union);
var _type = require('../type');var _type2 = _interopRequireDefault(_type);function _interopRequireDefault(obj) {return obj && obj.__esModule ? obj : { default: obj };}


var id = x => x;

var Just = _type2.default`Just`((0, _ramda.complement)(_ramda.isNil));
var Nothing = _type2.default`Nothing`(_ramda.isNil);

var Maybe = _union2.default`Maybe`({ Just, Nothing }, {
  map: ctx => mapFunction => Maybe(ctx.case({
    Just: mapFunction,
    Nothing: id })),

  chain: ctx => chainFunction => ctx.case({
    Just: chainFunction,
    Nothing: () => ctx }),

  filter: ctx => filterPredicate => ctx.chain(
  data => filterPredicate(data) ?
  Maybe(data) :
  Maybe()),

  reject: ctx => rejectPredicate => ctx.chain(
  data => rejectPredicate(data) ?
  Maybe() :
  Maybe(data)) });exports.default =



Maybe;
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