Add Foldable extension collectFirstSomeM #2366
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| * }}} | ||
| */ | ||
| def collectFirstSomeM[G[_], B](f: A => G[Option[B]])(implicit F: Foldable[F], G: Monad[G]): G[Option[B]] = | ||
| F.foldRight(fa, Eval.now(OptionT.none[G, B]))((a, lb) => |
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Would it be possible to implement this without OptionT? I think there's some overhead involved when wrapping values in monad transformers, and this is library code so it shouldn't be that problematic to use the wrapped values directly
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Sure, it would. Will do if you think it's worth it.
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Yeah let's try to do it as efficiently as possible :)
| def collectFirstSomeM[G[_], B](f: A => G[Option[B]])(implicit F: Foldable[F], G: Monad[G]): G[Option[B]] = | ||
| F.foldRight(fa, Eval.now(G.pure(Option.empty[B])))((a, lb) => | ||
| Eval.now(G.flatMap(f(a)) { | ||
| case s @ Some(_) => G.pure(s) |
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We could also match on None first and then add case s - we'll avoid an instance check and cast, so it could be good for performance. Not sure if the difference is significant though, we'd need to benchmark. Feel free to ignore this comment ;)
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Got it. Let me perform some jmh benchmarks.
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@kubukoz JMH proved you right :)
| F.foldRight(fa, Eval.now(OptionT.none[G, B]))((a, lb) => | ||
| Eval.now(OptionT(f(a)).orElse(lb.value)) | ||
| ).value.value | ||
| F.foldRight(fa, Eval.now(G.pure(Option.empty[B])))((a, lb) => |
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What's the preferred way to restart a failed Travis build if no file changes needed? push force? |
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Add an empty commit, I guess. `git commit --allow-empty`
…On Sat, Aug 11, 2018, 15:01 λoλcat ***@***.***> wrote:
What's the preferred way to restart a failed Travis build if no file
changes needed? push force?
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* Add Foldable extension collectFirstSomeM * Implement without OptionT * Optimize pattern matching * Empty commit
Monadic version of
collectFirstSome. Implemented as a syntax extension for binary compatibility.