Merge pull request #244 from puffnfresh/feature/option-optics

jbgi · jbgi · commit 406d125d981f · 2016-05-12T08:10:14.000+02:00
Add some optics for Option
diff --git a/core/src/main/java/fj/data/Option.java b/core/src/main/java/fj/data/Option.java
@@ -19,6 +19,8 @@
 import fj.Equal;
 import fj.Ord;
 import fj.Hash;
+import fj.data.optic.Prism;
+import fj.data.optic.PPrism;
 import static fj.Function.*;
 import static fj.P.p;
 import static fj.Unit.unit;
@@ -30,6 +32,8 @@
 import static fj.data.Validation.parseInt;
 import static fj.data.Validation.parseLong;
 import static fj.data.Validation.parseShort;
+import static fj.data.optic.Prism.prism;
+import static fj.data.optic.PPrism.pPrism;
 import static fj.Show.optionShow;
 
 import java.util.Collection;
@@ -883,4 +887,34 @@ public static <A> F<Option<Option<A>>, Option<A>> join() {
    * A function that parses a string to a short.
    */
   public static final F<String, Option<Short>> parseShort = s -> parseShort(s).toOption();
+
+  public static final class Optic {
+
+    private Optic() {
+      throw new UnsupportedOperationException();
+    }
+
+    /**
+     * None prism
+     */
+    public static <A> Prism<Option<A>, Unit> none() {
+      return prism(o -> o.option(Option.some(Unit.unit()), a -> Option.none()), u -> Option.none());
+    }
+
+    /**
+     * Polymorphic Some prism
+     */
+    public static <A, B> PPrism<Option<A>, Option<B>, A, B> pSome() {
+      return pPrism(o -> o.<Either<Option<B>, A>>map(Either::right).orSome(Either.left(Option.none())), Option::some);
+    }
+
+    /**
+     * Monomorphic Some prism
+     */
+    public static <A> Prism<Option<A>, A> some() {
+      return new Prism<>(pSome());
+    }
+
+  }
+
 }
diff --git a/props-core-scalacheck/src/main/scala/fj/package.scala b/props-core-scalacheck/src/main/scala/fj/package.scala
@@ -1,5 +1,5 @@
 import fj.Equal
-import fj.data.List
+import fj.data.{Option, List}
 package object fj {
   implicit def Function1F[A, B](g: A => B): F[A, B] = new F[A, B] {
     def f(a: A) = g(a)
@@ -16,9 +16,11 @@ package object fj {
   implicit def intEqual: Equal[Int] = Equal.equal({(i1:Int, i2:Int) => Boolean.box((i1 == i2))})
 
   implicit def unitEqual: Equal[Unit] = Equal.anyEqual()
-  
+
   implicit def listEqual[A](implicit aEq: Equal[A]): Equal[List[A]] = Equal.listEqual(aEq)
-  
+
+  implicit def optionEqual[A](implicit aEq: Equal[A]): Equal[Option[A]] = Equal.optionEqual(aEq)
+
   implicit def p2Equal[A, B](implicit aEq: Equal[A], bEq: Equal[B]): Equal[P2[A, B]] = Equal.p2Equal(aEq, bEq)
   
 }
diff --git a/props-core-scalacheck/src/test/scala/fj/data/CheckOption.scala b/props-core-scalacheck/src/test/scala/fj/data/CheckOption.scala
@@ -1,9 +1,11 @@
 package fj
 package data
 
+import fj.data.optic.PrismLaws
 import org.scalacheck.Prop._
 import ArbitraryOption.arbitraryOption
 import ArbitraryP.arbitraryP1
+import ArbitraryUnit._
 import Equal.{optionEqual, stringEqual}
 import Unit.unit
 import Option.{none, some, join}
@@ -84,4 +86,10 @@ object CheckOption extends Properties("Option") {
     a.isNone || optionEqual(stringEqual).eq(
       join(a),
       a.some))
+
+  property("Optic.pSome") = PrismLaws[Option[String], String](Option.Optic.pSome())
+
+  property("Optic.some") = PrismLaws[Option[String], String](Option.Optic.some())
+
+  property("Optic.none") = PrismLaws[Option[Unit], Unit](Option.Optic.none())
 }
