mezzanine/es/data-types/maybe.js

Fantasy land union types with pattern matching

import { complement, isNil } from 'ramda';

import Union from '../union';
import Type from '../type';


var id = x => x;

var Just = Type`Just`(complement(isNil));
var Nothing = Type`Nothing`(isNil);

var Maybe = Union`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)) });



export default Maybe;
//# sourceMappingURL=maybe.js.map