Prisms for Either

arrow-libs/optics/arrow-optics/api/arrow-optics.api

@@ -598,13 +598,17 @@ public final class arrow/optics/POptionalGetter$DefaultImpls {
 public abstract interface class arrow/optics/PPrism : arrow/optics/PEvery, arrow/optics/POptional, arrow/optics/POptionalGetter, arrow/optics/PSetter, arrow/optics/PTraversal {
 	public static final field Companion Larrow/optics/PPrism$Companion;
 	public abstract fun compose (Larrow/optics/PPrism;)Larrow/optics/PPrism;
+	public static fun eitherLeft ()Larrow/optics/PPrism;
+	public static fun eitherRight ()Larrow/optics/PPrism;
 	public abstract fun first ()Larrow/optics/PPrism;
 	public abstract fun foldMap (Larrow/typeclasses/Monoid;Ljava/lang/Object;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public abstract fun getOrModify (Ljava/lang/Object;)Larrow/core/Either;
 	public abstract fun left ()Larrow/optics/PPrism;
 	public abstract fun liftNullable (Lkotlin/jvm/functions/Function1;)Lkotlin/jvm/functions/Function1;
 	public abstract fun modify (Ljava/lang/Object;Lkotlin/jvm/functions/Function1;)Ljava/lang/Object;
 	public static fun none ()Larrow/optics/PPrism;
+	public static fun pLeft ()Larrow/optics/PPrism;
+	public static fun pRight ()Larrow/optics/PPrism;
 	public static fun pSome ()Larrow/optics/PPrism;
 	public abstract fun plus (Larrow/optics/PPrism;)Larrow/optics/PPrism;
 	public abstract fun reverseGet (Ljava/lang/Object;)Ljava/lang/Object;
@@ -615,11 +619,15 @@ public abstract interface class arrow/optics/PPrism : arrow/optics/PEvery, arrow
 }
 
 public final class arrow/optics/PPrism$Companion {
+	public final fun eitherLeft ()Larrow/optics/PPrism;
+	public final fun eitherRight ()Larrow/optics/PPrism;
 	public final fun id ()Larrow/optics/PIso;
 	public final fun invoke (Lkotlin/jvm/functions/Function1;Lkotlin/jvm/functions/Function1;)Larrow/optics/PPrism;
 	public final fun none ()Larrow/optics/PPrism;
 	public final fun only (Ljava/lang/Object;Lkotlin/jvm/functions/Function2;)Larrow/optics/PPrism;
 	public static synthetic fun only$default (Larrow/optics/PPrism$Companion;Ljava/lang/Object;Lkotlin/jvm/functions/Function2;ILjava/lang/Object;)Larrow/optics/PPrism;
+	public final fun pLeft ()Larrow/optics/PPrism;
+	public final fun pRight ()Larrow/optics/PPrism;
 	public final fun pSome ()Larrow/optics/PPrism;
 	public final fun some ()Larrow/optics/PPrism;
 }
@@ -813,6 +821,15 @@ public final class arrow/optics/dsl/AtKt {
 	public static final fun at (Larrow/optics/PTraversal;Larrow/optics/typeclasses/At;Ljava/lang/Object;)Larrow/optics/PTraversal;
 }
 
+public final class arrow/optics/dsl/EitherKt {
+	public static final fun getLeft (Larrow/optics/POptional;)Larrow/optics/POptional;
+	public static final fun getLeft (Larrow/optics/PPrism;)Larrow/optics/PPrism;
+	public static final fun getLeft (Larrow/optics/PTraversal;)Larrow/optics/PTraversal;
+	public static final fun getRight (Larrow/optics/POptional;)Larrow/optics/POptional;
+	public static final fun getRight (Larrow/optics/PPrism;)Larrow/optics/PPrism;
+	public static final fun getRight (Larrow/optics/PTraversal;)Larrow/optics/PTraversal;
+}
+
 public final class arrow/optics/dsl/EveryKt {
 	public static final fun every (Larrow/optics/Fold;Larrow/optics/PEvery;)Larrow/optics/Fold;
 	public static final fun every (Larrow/optics/PIso;Larrow/optics/PEvery;)Larrow/optics/PEvery;

arrow-libs/optics/arrow-optics/src/commonMain/kotlin/arrow/optics/Prism.kt

@@ -7,7 +7,10 @@ import arrow.core.Some
 import arrow.core.compose
 import arrow.core.flatMap
 import arrow.core.identity
+import arrow.core.left
+import arrow.core.right
 import arrow.typeclasses.Monoid
+import kotlin.jvm.JvmName
 import kotlin.jvm.JvmStatic
 
 /**
@@ -172,6 +175,48 @@ public interface PPrism<S, T, A, B> : POptional<S, T, A, B>, PSetter<S, T, A, B>
         getOrModify = { option -> option.fold({ Either.Right(Unit) }, { Either.Left(option) }) },
         reverseGet = { _ -> None }
       )
+
+    /**
+     * [Prism] to focus into an [arrow.core.Either.Left]
+     */
+    @JvmStatic @JvmName("eitherLeft")
+    public fun <L, R> left(): Prism<Either<L, R>, L> = pLeft()
+
+    /**
+     * [Prism] to focus into an [arrow.core.Either.Right]
+     */
+    @JvmStatic @JvmName("eitherRight")
+    public fun <L, R> right(): Prism<Either<L, R>, R> = pRight()
+
+    /**
+     * Polymorphic [PPrism] to focus into an [arrow.core.Either.Left]
+     */
+    @JvmStatic
+    public fun <L, R, E> pLeft(): PPrism<Either<L, R>, Either<E, R>, L, E> =
+      Prism(
+        getOrModify = { e ->
+          when (e) {
+            is Either.Left -> e.value.right()
+            is Either.Right -> e.left()
+          }
+        },
+        reverseGet = { it.left() }
+      )
+
+    /**
+     * Polymorphic [PPrism] to focus into an [arrow.core.Either.Right]
+     */
+    @JvmStatic
+    public fun <L, R, B> pRight(): PPrism<Either<L, R>, Either<L, B>, R, B> =
+      PPrism(
+        getOrModify = { e ->
+          when (e) {
+            is Either.Left -> e.left()
+            is Either.Right -> e.value.right()
+          }
+        },
+        reverseGet = { it.right() }
+      )
   }
 }
 

arrow-libs/optics/arrow-optics/src/commonMain/kotlin/arrow/optics/dsl/either.kt

@@ -0,0 +1,56 @@
+package arrow.optics.dsl
+
+import arrow.core.Either
+import arrow.optics.Lens
+import arrow.optics.Optional
+import arrow.optics.PPrism
+import arrow.optics.Prism
+import arrow.optics.Traversal
+
+/**
+ * DSL to compose a [Prism] with focus [Either] with a [Prism] with a focus of [Either.Left]<[L]>
+ *
+ * @receiver [Prism] with a focus in [Either]
+ * @return [Prism] with a focus in [L]
+ */
+public inline val <A, L, R> Prism<A, Either<L, R>>.left: Prism<A, L> inline get() = this.compose(PPrism.left())
+
+/**
+ * DSL to compose a [Optional] with focus [Either] with a [Prism] with a focus of [Either.Left]<[L]>
+ *
+ * @receiver [Lens] or [Optional] with a focus in [Either]
+ * @return [Optional] with a focus in [L]
+ */
+public inline val <A, L, R> Optional<A, Either<L, R>>.left: Optional<A, L> inline get() = this.compose(PPrism.left())
+
+/**
+ * DSL to compose a [Traversal] with focus [Either] with a [Prism] with a focus of [Either.Left]<[L]>
+ *
+ * @receiver [Traversal] with a focus in [Either]
+ * @return [Traversal] with a focus in [L]
+ */
+public inline val <A, L, R> Traversal<A, Either<L, R>>.left: Traversal<A, L> inline get() = this.compose(PPrism.left())
+
+/**
+ * DSL to compose a [Prism] with focus [Either] with a [Prism] with a focus of [Either.Right]<[R]>
+ *
+ * @receiver [Prism] with a focus in [Either]
+ * @return [Prism] with a focus in [R]
+ */
+public inline val <A, L, R> Prism<A, Either<L, R>>.right: Prism<A, R> inline get() = this.compose(PPrism.right())
+
+/**
+ * DSL to compose a [Optional] with focus [Either] with a [Prism] with a focus of [Either.Right]<[R]>
+ *
+ * @receiver [Lens] or [Optional] with a focus in [Either]
+ * @return [Optional] with a focus in [R]
+ */
+public inline val <A, L, R> Optional<A, Either<L, R>>.right: Optional<A, R> inline get() = this.compose(PPrism.right())
+
+/**
+ * DSL to compose a [Traversal] with focus [Either] with a [Prism] with a focus of [Either.Right]<[R]>
+ *
+ * @receiver [Traversal] with a focus in [Either]
+ * @return [Traversal] with a focus in [R]
+ */
+public inline val <A, L, R> Traversal<A, Either<L, R>>.right: Traversal<A, R> inline get() = this.compose(PPrism.right())