when

Match Left or Right values using types

This when(This either, Matcher matcher)
This
when
(
Matcher
This : Either!(Left, Right)
Left
Right
)
(
This either
,
Matcher matcher
)
if (
isCallable!Matcher
)
auto when(This either, T newValue)
Either!(NewLeft!(This, T), NewRight!(This, T)) when(This either, T result)

Examples

'when' is called with the left value function when the monad isLeft is true

auto either = Either!(int, bool)(1);
string result = "none";

either
  .when((int value) {
    result = "left";
  })
  .when((bool value) {
    result = "right";
  });

result.should.equal("left");

it calls the 'when' with right value function when the monad isRight is true

auto either = Either!(int, bool)(true);
string result = "none";

either
  .when((int value) {
    result = "left";
  })
  .when((bool value) {
    result = "right";
  });

result.should.equal("right");

it does not call the 'when' function when the types don't match

auto either = Either!(int, bool)(true);
string result = "none";

either
  .when((double value) {
    result = "double";
  })
  .when((string value) {
    result = "string";
  });

result.should.equal("none");

it returns the binded value when the 'when' function returns

auto either = Either!(int, bool)(1);
bool message;

auto result = either
  .when((int value) {
    return true;
  })
  .when((bool value) {
    message = value;
  });

result.isRight.should.equal(true);
message.should.equal(true);

when

Examples

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