import { Option } from 'fp-ts/lib/Option'; // CommonJS
import { Option } from 'fp-ts/es6/Option'; // ESModule
import * as O from 'fp-ts/lib/Option'
import { identity } from 'fp-ts/lib/function'
import { pipeable } from 'fp-ts'

pipeable.pipe(
	O.some(42), // O.Option<number>
	O.chain(n => n === 42 ? O.some('Answer to Everything') : O.none), // (ma: O.Option<number>) => O.Option<string>
	O.fold(() => 'No Answer', identity) // (ma: O.Option<string>) => string
) // string
import * as E from 'fp-ts/lib/Either';
import { sequenceT } from 'fp-ts/lib/Apply';
import * as A from 'fp-ts/lib/Array';

const hoge = E.getApplicativeValidation(A.getMonoid<string>());
console.log(sequenceT(hoge)(E.left(['a']), E.left(['b'])));
// { _tag: 'Left', left: [ 'a', 'b' ] }