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Put liftT on the companion object of XorT #1215

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merged 5 commits into from
Aug 20, 2016
Merged

Put liftT on the companion object of XorT #1215

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20b8a58
Put liftT on the companion object of XorT
Jul 18, 2016
bbf98aa
Put liftT into the XorTfunctions trait and alias it for right
Jul 18, 2016
ff457d9
Make the XorT.right a scaladoc link
Jul 20, 2016
480b8f3
Fix missing implicit evidence needed, add doctest example
Jul 21, 2016
1e277cd
Use the implicits import instead of piece-meal
Jul 21, 2016
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17 changes: 16 additions & 1 deletion core/src/main/scala/cats/data/XorT.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -219,6 +219,21 @@ trait XorTFunctions {

final def pure[F[_], A, B](b: B)(implicit F: Applicative[F]): XorT[F, A, B] = right(F.pure(b))

/**
* Alias for [[XorT.right]]
* {{{
* scala> import cats.data.XorT
* scala> import cats.implicits._
* scala> val o: Option[Int] = Some(3)
* scala> val n: Option[Int] = None
* scala> XorT.liftT(o)
* res0: cats.data.XorT[Option,Nothing,Int] = XorT(Some(Right(3)))
* scala> XorT.liftT(n)
* res1: cats.data.XorT[Option,Nothing,Int] = XorT(None)
* }}}
*/
final def liftT[F[_], A, B](fb: F[B])(implicit F: Functor[F]): XorT[F, A, B] = right(fb)
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why do we even need Functor here?

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Without the implicit evidence for a Functor it won't compile since right needs one.

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Indeed. I made the mistake of believing that was just Xor.right Sorry for the noise.

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All good, I'm just happy I could answer :)


/** Transforms an `Xor` into an `XorT`, lifted into the specified `Applicative`.
*
* Note: The return type is a FromXorPartiallyApplied[F], which has an apply method
Expand Down Expand Up @@ -280,7 +295,7 @@ private[data] abstract class XorTInstances extends XorTInstances1 {
type TC[M[_]] = Functor[M]

def liftT[M[_]: Functor, A](ma: M[A]): XorT[M, E, A] =
XorT(Functor[M].map(ma)(Xor.right))
XorT.liftT(ma)
}

implicit def catsMonoidForXorT[F[_], L, A](implicit F: Monoid[F[L Xor A]]): Monoid[XorT[F, L, A]] =
Expand Down