replace extra method with string parameter

[bakkot]

I really don't like having two almost identical methods which differ only in their handling of an edge case. This PR removes sliding and adds a string parameter to windows which controls the behavior in the case of an undersized iterator, with possible values "discard" (the default) or "truncate" (the previous behavior for sliding). Feel free to bikeshed the values if you have strong opinions. I left out "throw" but I guess it's also a valid thing to want (edit: #25).

I've chosen to go with a string argument instead of a boolean so that we can later turn this into an options bag if we really feel the need. Boolean would also be fine but makes it harder to do that change (because we said we'd allow coercion to boolean).

Fixes #23 (by causing it not to be a problem).

[bakkot]

In plenary today @waldemarhorwat suggested doing "discard" and "short", which I'm also happy with.

[michaelficarra]

I think the parameter should use a consistent part of speech, preferably verbs. Past participles "discarded"/"omitted" and "undersized"/"truncated" would also be fine.

[bakkot]

"Discard", noun, "one that is cast off or rejected".

[michaelficarra]

😛 That's not the form being used here and you know it.

[js-choi]

What about “discard” and “shorten”?

[michaelficarra]

That seems fine. It's pretty much synonymous with truncate to me 🤷‍♂️.

[jridgewell]

I would throw in partial, since that can't be confused with truncating the input array. Maybe full/partial?

[bakkot]

"full" is confusing to me because you're getting fewer outputs in that case. I'd maybe accept "only-full"? But that's kind of verbose.

[bakkot]

To address part of speech concerns, "discard" and "output-short", maybe?