<A, B>(f: (a: A) => B): (self: A | undefined) => B | undefined
<A, B>(self: A | undefined, f: (a: A) => B): B | undefinedMaps a defined value with f, or returns undefined unchanged.
When to use
Use to apply a pure transformation to an A | undefined value while
preserving undefined as absence.
mappingmatch
Source effect/UndefinedOr.ts:314 lines
export const const map: {
<A, B>(f: (a: A) => B): (
self: A | undefined
) => B | undefined
<A, B>(self: A | undefined, f: (a: A) => B):
| B
| undefined
}
Maps a defined value with f, or returns undefined unchanged.
When to use
Use to apply a pure transformation to an A | undefined value while
preserving undefined as absence.
map: {
<function (type parameter) A in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedA, function (type parameter) B in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedB>(f: (a: A) => Bf: (a: Aa: function (type parameter) A in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedA) => function (type parameter) B in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedB): (self: A | undefinedself: function (type parameter) A in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedA | undefined) => function (type parameter) B in <A, B>(f: (a: A) => B): (self: A | undefined) => B | undefinedB | undefined
<function (type parameter) A in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedA, function (type parameter) B in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedB>(self: A | undefinedself: function (type parameter) A in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedA | undefined, f: (a: A) => Bf: (a: Aa: function (type parameter) A in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedA) => function (type parameter) B in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedB): function (type parameter) B in <A, B>(self: A | undefined, f: (a: A) => B): B | undefinedB | undefined
} = import dualdual(2, (self: anyself, f: anyf) => (self: anyself === var undefinedundefined ? var undefinedundefined : f: anyf(self: anyself)))