Add empty to State and StateT objects #2533
Conversation
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Seems like there's still a bincompat issue for 2.11 |
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Ah, right. 2.11 doesn't like methods added to traits. But this should be fine with an exception, no? |
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We can add new methods by creating a new trait and mixing it in, similar to what we've been doing with the syntax additions :) |
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Smart. I've updated the commit accordingly. |
Codecov Report
@@ Coverage Diff @@
## master #2533 +/- ##
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+ Coverage 95.17% 95.17% +<.01%
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Files 359 359
Lines 6553 6555 +2
Branches 278 286 +8
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+ Hits 6237 6239 +2
Misses 316 316
Continue to review full report at Codecov.
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And we're green! |
| @@ -223,6 +223,11 @@ object IndexedStateT extends IndexedStateTInstances with CommonStateTConstructor | |||
| IndexedStateT(_ => F.map(fsb)(s => (s, ()))) | |||
| } | |||
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| private[data] trait CommonStateTConstructors0 extends CommonStateTConstructors { | |||
| def empty[F[_], S, A: Monoid](implicit F: Applicative[F]): IndexedStateT[F, S, S, A] = | |||
| pure(Monoid[A].empty) | |||
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Is there a reason to use : Monoid for A but not use : Applicative for F? I'd be inclined to not use the syntactic sugar for either so you can avoid do something like F.pure(A.empty) and avoid an extra Monoid.apply[A] call.
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@ceedubs Is this fine with you now? |
| @@ -223,6 +223,11 @@ object IndexedStateT extends IndexedStateTInstances with CommonStateTConstructor | |||
| IndexedStateT(_ => F.map(fsb)(s => (s, ()))) | |||
| } | |||
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| private[data] trait CommonStateTConstructors0 extends CommonStateTConstructors { | |||
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Is there any particular reason to introduce this new trait as opposed to just putting this method directly into the object?
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Binary compatibility: #2533 (comment)
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To be precise, the function is not only provided on the IndexedStateT object, but also on StateT. This is the reason why it has to go into a trait in the first place.
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Oh okay that makes sense. Thanks for the explanation.
Co-authored-by: Lars Hupel <lars.hupel@mytum.de>
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@ceedubs Updated accordingly. |
Work by @sderosiaux in #2294. Rebased to current master. For some reason, the bincompat error also went away (at least locally).