[swift-evolution] [Review] SE-0187: Introduce Sequence.filterMap(_:)

[Brent Royal-Gordon]

> On Nov 8, 2017, at 9:29 PM, Paul Cantrell via swift-evolution <swift-evolution at swift.org> wrote:
> 
> The problem in the Doodads example is that the name flatMap is used to identify two distinct intents: concatenating arrays and filtering nils. One can argue that those two operations are, in some lofty abstract sense, if you squint, two instances of some more general pattern — but I don’t think it’s fair to say that they represent the same intent. These separate intents deserve separate names.

I think that's the crux of it.

I think we might be better off renaming the maps on `Optional` and then naming the `Sequence` operation analogously. For instance:

	Optional.map(transform) => Optional.pass(to: transform)
	Optional.flatMap(transform) => Optional.chain(to: transform)

Then this would be a natural choice:

	Sequence.flatMap(transform) => Sequence.chainMap(transform)

Alternatively, we could think of a name for "removing optionality from a sequence" and then use that name. For example, borrowing a name from Ruby:

	(Sequence where Element == T?).compact()
	Sequence.compactMap(transform)

Actually, "unwrapped" might be a better name than "compact", since we use that term.

-- 
Brent Royal-Gordon
Architechies

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