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djfm/chain-do-maybe.js

Created September 18, 2016 14:51
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chain-do-maybe.js
const just = x => Promise.resolve(x);
const nothing = () => Promise.reject();
chain(
() => just(1),
() => nothing(),
(_, x, y) => just(x / y)
)()
.should.be.rejected;
chain(
() => just(1),
() => just(2),
(_, x, y) => just(x / y)
)()
.should.eventually.equal(0.5);
// try it: https://jsfiddle.net/r7haet84/1/
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