MonadRec Implementation for Choice3

7h3kk1d · jnape · commit ae94ce623737 · 2019-09-10T15:41:15.000-05:00
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/choice/Choice3.java b/src/main/java/com/jnape/palatable/lambda/adt/choice/Choice3.java
@@ -6,17 +6,21 @@
 import com.jnape.palatable.lambda.adt.hlist.HList;
 import com.jnape.palatable.lambda.adt.hlist.Tuple3;
 import com.jnape.palatable.lambda.functions.Fn1;
+import com.jnape.palatable.lambda.functions.recursion.RecursiveResult;
 import com.jnape.palatable.lambda.functions.specialized.Pure;
 import com.jnape.palatable.lambda.functor.Applicative;
 import com.jnape.palatable.lambda.functor.Bifunctor;
 import com.jnape.palatable.lambda.functor.Functor;
 import com.jnape.palatable.lambda.functor.builtin.Lazy;
 import com.jnape.palatable.lambda.monad.Monad;
+import com.jnape.palatable.lambda.monad.MonadRec;
 import com.jnape.palatable.lambda.traversable.Traversable;
 
 import java.util.Objects;
 
 import static com.jnape.palatable.lambda.functions.builtin.fn2.Into3.into3;
+import static com.jnape.palatable.lambda.functions.recursion.RecursiveResult.terminate;
+import static com.jnape.palatable.lambda.functions.recursion.Trampoline.trampoline;
 import static com.jnape.palatable.lambda.functor.builtin.Lazy.lazy;
 
 /**
@@ -32,7 +36,19 @@ public abstract class Choice3<A, B, C> implements
         CoProduct3<A, B, C, Choice3<A, B, C>>,
         Monad<C, Choice3<A, B, ?>>,
         Bifunctor<B, C, Choice3<A, ?, ?>>,
-        Traversable<C, Choice3<A, B, ?>> {
+        Traversable<C, Choice3<A, B, ?>>,
+        MonadRec<C, Choice3<A, B, ?>> {
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    public <D> Choice3<A, B, D> trampolineM(Fn1<? super C, ? extends MonadRec<RecursiveResult<C, D>, Choice3<A, B, ?>>> fn) {
+        return flatMap(trampoline(c -> fn.apply(c).<Choice3<A, B, RecursiveResult<C, D>>>coerce()
+                .match(a -> terminate(a(a)),
+                        b -> terminate(b(b)),
+                        r -> r.fmap(Choice3::c))));
+    }
 
     private Choice3() {
     }
@@ -68,7 +84,7 @@ public final Choice2<A, B> converge(Fn1<? super C, ? extends CoProduct2<A, B, ?>
      */
     @Override
     public final <D> Choice3<A, B, D> fmap(Fn1<? super C, ? extends D> fn) {
-        return Monad.super.<D>fmap(fn).coerce();
+        return MonadRec.super.<D>fmap(fn).coerce();
     }
 
     /**
@@ -109,7 +125,7 @@ public <D> Choice3<A, B, D> pure(D d) {
      */
     @Override
     public <D> Choice3<A, B, D> zip(Applicative<Fn1<? super C, ? extends D>, Choice3<A, B, ?>> appFn) {
-        return Monad.super.zip(appFn).coerce();
+        return MonadRec.super.zip(appFn).coerce();
     }
 
     /**
@@ -128,15 +144,15 @@ public <D> Lazy<Choice3<A, B, D>> lazyZip(
      */
     @Override
     public <D> Choice3<A, B, D> discardL(Applicative<D, Choice3<A, B, ?>> appB) {
-        return Monad.super.discardL(appB).coerce();
+        return MonadRec.super.discardL(appB).coerce();
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public <D> Choice3<A, B, C> discardR(Applicative<D, Choice3<A, B, ?>> appB) {
-        return Monad.super.discardR(appB).coerce();
+        return MonadRec.super.discardR(appB).coerce();
     }
 
     /**
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/choice/Choice3Test.java b/src/test/java/com/jnape/palatable/lambda/adt/choice/Choice3Test.java
@@ -6,11 +6,7 @@
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
-import testsupport.traits.ApplicativeLaws;
-import testsupport.traits.BifunctorLaws;
-import testsupport.traits.FunctorLaws;
-import testsupport.traits.MonadLaws;
-import testsupport.traits.TraversableLaws;
+import testsupport.traits.*;
 
 import static com.jnape.palatable.lambda.adt.choice.Choice3.a;
 import static com.jnape.palatable.lambda.adt.choice.Choice3.b;
@@ -33,7 +29,7 @@ public void setUp() {
         c = Choice3.c(true);
     }
 
-    @TestTraits({FunctorLaws.class, ApplicativeLaws.class, MonadLaws.class, BifunctorLaws.class, TraversableLaws.class})
+    @TestTraits({FunctorLaws.class, ApplicativeLaws.class, MonadLaws.class, BifunctorLaws.class, TraversableLaws.class, MonadRecLaws.class})
     public Subjects<Choice3<String, Integer, Boolean>> testSubjects() {
         return subjects(a("foo"), b(1), c(true));
     }
