mapOrElse

Maps a Expected<T, E> to U by applying a function to a contained value, or a fallback function to a contained error value.

Both functions has to be of the same return type.

This function can be used to unpack a successful result while handling an error.

template mapOrElse(alias valueOp, alias errorOp)

@safe

mapOrElse

(

T

E

H

)

(

auto ref Expected!(T, E, H) self

)

if (

is(typeof(errorOp(self.error))) &&

(

(

is(T == void) &&

is(typeof(valueOp()) == typeof(errorOp(self.error)))

) ||

(

!is(T == void) &&

is(typeof(valueOp(self.value)) == typeof(errorOp(self.error)))

)

)

)

Members

Functions

mapOrElse auto mapOrElse(auto ref Expected!(T, E, H) self): The actual mapOrElse function.

Parameters

valueOp: function called to map Expected value
errorOp: function called to map Expected error

Return Value

A new Expected object containing the result.

Examples

assert(ok(42).mapOrElse!(v => v/2, e => 0) == 21);
assert(ok().mapOrElse!(() => true, e => false));
assert(err!int("foo").mapOrElse!(v => v/2, e => 42) == 42);
assert(!err("foo").mapOrElse!(() => true, e => false));

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Source

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