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Add sum: (F[A], F[B]) => F[A Either B] #3112

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Krever opened this issue Oct 13, 2019 · 1 comment · Fixed by #3124
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Add sum: (F[A], F[B]) => F[A Either B] #3112

Krever opened this issue Oct 13, 2019 · 1 comment · Fixed by #3124

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@Krever
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Krever commented Oct 13, 2019

Hey, I have

type X[T] = Kleisli[OptionT[F, *], Foo, T]

and would like to go from (X[A], X[B]) to X[Either[A, B]].

So similar to what <+> does (e.g. in http4s) but on two different types joined by Either. Right now I map and use <+> afterwards.

Signature proposed by @LukaJCB :

def sum[F[_]: SemigroupK, Functor, A, B](fa: F[A], fb: F[B]): F[A Either B]
@pk044
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pk044 commented Oct 23, 2019

i'd be happy to give it a try :)

pk044 added a commit to pk044/cats that referenced this issue Nov 4, 2019
@pk044
typelevel#3112 adding implementation
194490e
pk044 added a commit to pk044/cats that referenced this issue Nov 4, 2019
@pk044
typelevel#3112 added documentation with example
e705634
@pk044 pk044 mentioned this issue Nov 4, 2019
Merged
LukaJCB pushed a commit that referenced this issue Nov 5, 2019
@pk044 @LukaJCB
SemigroupK sum: F[A], F[B] => F[A Either B] (#3124)
6d191a5 
* #3112 adding implementation

* #3112 added documentation with example

* adding pk044 to AUTHORS.md

* formatting

* fixed doctest

* fixed doctest

* used different type in example
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SemigroupK sum: F[A], F[B] => F[A Either B] pk044/cats
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@Krever @pk044