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seasonedcc / composable-functions

Types and functions to make composition easy and safe
MIT License
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Tight composition types #121

Closed diogob closed 9 months ago

diogob commented 10 months ago

This should allow only valid types when using the composition primitives (a.k.a. Composable operations). Since the primitives do not have parsers on their input the type-safety not only makes sense but becomes essential to writing robust compositions.

It is important to note that we rely on a type conversion from a union to a tuple. This type helper (generously shared here) uses the internal union order which means that the order when converting from a Record to a tuple is not stable. This is irrelevant to type our collect function since it is applied in parallel. But I'm leaving this long note here to explain why implementing a collectSequence with a Record input would be very challenging.

diogob commented 10 months ago

@gustavoguichard I think I got collect working. Actually the restriction I found only impedes us from typing collectSequence since there we need to preserve the order of the keys.

diogob commented 10 months ago

~@gustavoguichard just realized there is still some work to do generalizing some types such as the Unpack ones. I have converted back to draft and will mark as ready for review as soon as I finish those bits.~

diogob commented 10 months ago

Nevermind generalizing the Unpack types. I just tried and I remembered why I haven't done it so far. It's not trivial and also not necessary for a release. Once we start gearing up to the major release we can revisit them.

gustavoguichard commented 10 months ago

Nevermind generalizing the Unpack types.

You mean being able to use Unpack with both df and composable?

diogob commented 10 months ago

Nevermind generalizing the Unpack types.

You mean being able to use Unpack with both df and composable?

That's what I meant, since these two types have the same name but they behave in quite different ways. The DF UnpackResult applies the ReturnType, and the composable UnpackResult just takes the result out of the promise. But I wouldn't worry about this for this PR.

diogob commented 9 months ago

I have a proposal for new naming conventions, will send in another PR to avoid muddying the waters here