Nothing if the original maybe is Nothing, or andMaybe
if the original maybe is Just.
You can think of this like a short-circuiting logical "and" operation on a
Maybe type. If maybe is just, then the result is the
andMaybe. If maybe is Nothing, the result is Nothing.
This is useful when you have another Maybe value you want to provide if and
only if you have a Just – that is, when you need to make sure that if you
Nothing, whatever else you're handing a Maybe to also gets a Nothing.
Notice that, unlike in map or its variants, the original maybe is
not involved in constructing the new Maybe.
import Maybe from 'true-myth/maybe';
const justA = Maybe.just('A');
const justB = Maybe.just('B');
const nothing: Maybe<number> = nothing();
console.log(Maybe.and(justB, justA).toString()); // Just(B)
console.log(Maybe.and(justB, nothing).toString()); // Nothing
console.log(Maybe.and(nothing, justA).toString()); // Nothing
console.log(Maybe.and(nothing, nothing).toString()); // Nothing
Nothing if the original maybe is Nothing, or andMaybe
if the original maybe is Just.
You can think of this like a short-circuiting logical "and" operation on a
Maybetype. Ifmaybeisjust, then the result is theandMaybe. IfmaybeisNothing, the result isNothing.This is useful when you have another
Maybevalue you want to provide if and only if you have aJust– that is, when you need to make sure that if youNothing, whatever else you're handing aMaybeto also gets aNothing.Notice that, unlike in
mapor its variants, the originalmaybeis not involved in constructing the newMaybe.Examples