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Axioms

maybeToLeft

maybeToLeft<T, R>(x, right): [Nothing] extends [T] ? IsEqual<T, Nothing> extends true ? Right<R> : Either<Just<T>, R> : Left<T>

Transforms a Maybe value into an Either type, returning a Left containing the Just value. If the Maybe is Nothing, it returns a Right with a specified default value.

Example

maybeToLeft("foo", "fallback")
// => {left: "foo"}


maybeToLeft(Nothing, "fallback")
// => {right: "fallback"}

Type Parameters

• T

The type held by Just in the Maybe.

• R

The type of the Right value in the returned Either.

Parameters

x

T

The Maybe value to transform. If it is a Just, it is returned as the Left part of an Either.

R

The default value to use for the Right part if x is Nothing.

Returns

[Nothing] extends [T] ? IsEqual<T, Nothing> extends true ? Right<R> : Either<Just<T>, R> : Left<T>

Either a Left containing the Just value or a Right with the default value.