Js.Option
Provide utilities for option
let isSomeValue: Js.Fn.arity2(('a => 'a => bool)) => 'a => option('a) => bool;
let equal:
Js.Fn.arity2(('a => 'b => bool)) =>
option('a) =>
option('b) =>
bool;
let andThen: Js.Fn.arity1(('a => option('b))) => option('a) => option('b);
let map: Js.Fn.arity1(('a => 'b)) => option('a) => option('b);
let filter: Js.Fn.arity1(('a => bool)) => option('a) => option('a);