Add ApplicativeAsk with subtyping (#231)

zio · Sep 21, 2020 · 869e9b9 · 869e9b9
1 parent 05a4920
commit 869e9b9
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/interop-cats/shared/src/main/scala/zio/interop/catsmtl.scala b/interop-cats/shared/src/main/scala/zio/interop/catsmtl.scala
@@ -31,6 +31,14 @@ abstract class CatsMtlInstances {
       def local[A](f: R => R)(fa: ZIO[R, E, A]): ZIO[R, E, A] = ZIO.accessM(fa provide f(_))
     }
 
+  implicit def zioApplicativeAsk[R1, R <: R1, E](
+    implicit ev: Applicative[ZIO[R, E, ?]]
+  ): ApplicativeAsk[ZIO[R, E, ?], R1] =
+    new DefaultApplicativeAsk[ZIO[R, E, ?], R1] {
+      override val applicative: Applicative[ZIO[R, E, *]] = ev
+      override def ask: ZIO[R, Nothing, R1]               = ZIO.environment
+    }
+
   implicit def zioApplicativeHandle[R, E](implicit ev: Applicative[ZIO[R, E, ?]]): ApplicativeHandle[ZIO[R, E, ?], E] =
     new DefaultApplicativeHandle[ZIO[R, E, ?], E] {
       val functor: Functor[ZIO[R, E, ?]]                                      = ev

diff --git a/interop-cats/shared/src/test/scala/zio/interop/catzMtlSpec.scala b/interop-cats/shared/src/test/scala/zio/interop/catzMtlSpec.scala
@@ -31,8 +31,9 @@ class catzMtlSpec extends catzSpecZIOBase {
     implicit tc => ApplicativeHandleTests[ZIO[Ctx, Error, *], Error].applicativeHandle[Int]
   )
 
-  def askSummoner[R, E]    = ApplicativeAsk[ZIO[R, E, *], R]
-  def localSummoner[R, E]  = ApplicativeLocal[ZIO[R, E, *], R]
-  def raiseSummoner[R, E]  = FunctorRaise[ZIO[R, E, *], E]
-  def handleSummoner[R, E] = ApplicativeHandle[ZIO[R, E, *], E]
+  def askSummoner[R, E]                    = ApplicativeAsk[ZIO[R, E, *], R]
+  def askSubtypingSummoner[R1, R <: R1, E] = ApplicativeAsk[ZIO[R, E, *], R1]
+  def localSummoner[R, E]                  = ApplicativeLocal[ZIO[R, E, *], R]
+  def raiseSummoner[R, E]                  = FunctorRaise[ZIO[R, E, *], E]
+  def handleSummoner[R, E]                 = ApplicativeHandle[ZIO[R, E, *], E]
 }