contraMap

Generates a new sink of type T2.

Given a transform closure, the following code is functionally equivalent:

sink.send(transform(value))

sink.contraMap(transform).send(value)

Trivia: Why is this called contraMap? - map turns Type<T> into Type<U> via (T)->U. - contraMap turns Type<T> into Type<U> via (U)->T

Another way to think about this is: map transforms a type by changing the output types of its API, while contraMap transforms a type by changing the input types of its API.