Sink

Abstract type for sinks. Values that implement the sink protocol are instances of Sink, which can be used for type testing.

Sink is not constructible directly.

assert_eq (type $ [].sink()) $Sink

Inherits

• Sinkable

Methods

put value

Writes a value to the sink.

Parameters

Name	Type	Description
value		the value to write

premap func

Wraps the sink so each value is transformed before it is written.

The pre prefix marks the direction: unlike Iter.map, which transforms values on their way out, premap transforms values on their way into the sink. A value that is both Iterable and Sinkable — an Array, say — therefore offers map and premap as separate methods running in opposite directions.

Parameters

Name	Type	Description
func		applied to each value before it is put

let acc = []
let out = acc.premap (do |x| x * 2)
out.put 3
assert_eq $acc [6]

prefilter pred

Wraps the sink so only values for which pred is truthy are written.

Because each wrapper transforms values on the way in, the outermost wrapper sees a value first — the reverse of an iterator chain.

Parameters

Name	Type	Description
pred		decides whether a value is written

let acc = []
let out = acc.prefilter (do |x| x % 2 == 0)
out.put 1
out.put 2
assert_eq $acc [2]