functionaljava · mperry · Jan 22, 2015 · Jan 22, 2015
diff --git a/core/src/main/java/fj/Equal.java b/core/src/main/java/fj/Equal.java
@@ -535,19 +535,19 @@ public static <A, B> Equal<Writer<A, B>> writerEqual(Equal<A> eq1, Equal<B> eq2)
   }
 
   /**
-   * Can the objects be checked for equality?
-   * @return True if the objects are not null and are an instance of the provided class.
-   */
-  public static boolean equalsValidationCheck(Object o1, Object o2) {
-    java.lang.Class<?> c = o1.getClass();
-    if (o1 == null || !c.isInstance(o1)) {
-      return false;
-    }
-    if (o2 == null || !c.isInstance(o2)) {
-      return false;
+   * @return Returns none if no equality can be determined by checking the nullity and reference values, else the equality
+   */
+  public static Option<Boolean> shallowEqualsO(Object o1, Object o2) {
+    if (o1 == null && o2 == null) {
+      return Option.some(true);
+    } else if (o1 == o2) {
+      return Option.some(true);
+    } else if (o1 != null && o2 != null) {
+      java.lang.Class<?> c = o1.getClass();
+      return c.isInstance(o2) ? Option.none() : Option.some(false);
+    } else {
+      return Option.some(false);
     }
-    return true;
-
   }
 
 }
diff --git a/core/src/main/java/fj/P1.java b/core/src/main/java/fj/P1.java
@@ -5,8 +5,6 @@
 import fj.data.Array;
 import fj.data.List;
 import fj.data.Stream;
-import fj.data.Validation;
-import fj.function.Try0;
 
 public abstract class P1<A> implements F0<A> {
 
@@ -244,8 +242,7 @@ public String toString() {
 
     @Override
     public boolean equals(Object other) {
-        return !Equal.equalsValidationCheck(this, other) ? false :
-                Equal.p1Equal(Equal.<A>anyEqual()).eq(this, (P1<A>) other);
+        return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p1Equal(Equal.<A>anyEqual()).eq(this, (P1<A>) other)));
     }
 
     @Override

diff --git a/core/src/main/java/fj/P2.java b/core/src/main/java/fj/P2.java
@@ -26,7 +26,7 @@ public abstract class P2<A, B> {
 
   @Override
   public boolean equals(Object other) {
-    return Equal.p2Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual()).eq(this, (P2<A, B>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p2Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual()).eq(this, (P2<A, B>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P3.java b/core/src/main/java/fj/P3.java
@@ -192,8 +192,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p3Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual()).eq(this, (P3<A, B, C>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p3Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual()).eq(this, (P3<A, B, C>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P4.java b/core/src/main/java/fj/P4.java
@@ -265,8 +265,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p4Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual()).eq(this, (P4<A, B, C, D>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p4Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual()).eq(this, (P4<A, B, C, D>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P5.java b/core/src/main/java/fj/P5.java
@@ -344,8 +344,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p5Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual()).eq(this, (P5<A, B, C, D, E>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p5Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual()).eq(this, (P5<A, B, C, D, E>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P6.java b/core/src/main/java/fj/P6.java
@@ -435,8 +435,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p6Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual()).eq(this, (P6<A, B, C, D, E, F>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p6Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual()).eq(this, (P6<A, B, C, D, E, F>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P7.java b/core/src/main/java/fj/P7.java
@@ -529,8 +529,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p7Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual(), Equal.<G>anyEqual()).eq(this, (P7<A, B, C, D, E, F, G>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p7Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual(), Equal.<G>anyEqual()).eq(this, (P7<A, B, C, D, E, F, G>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/P8.java b/core/src/main/java/fj/P8.java
@@ -635,8 +635,7 @@ public String toString() {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.p8Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual(), Equal.<G>anyEqual(), Equal.<H>anyEqual()).eq(this, (P8<A, B, C, D, E, F, G, H>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.p8Equal(Equal.<A>anyEqual(), Equal.<B>anyEqual(), Equal.<C>anyEqual(), Equal.<D>anyEqual(), Equal.<E>anyEqual(), Equal.<F>anyEqual(), Equal.<G>anyEqual(), Equal.<H>anyEqual()).eq(this, (P8<A, B, C, D, E, F, G, H>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/Array.java b/core/src/main/java/fj/data/Array.java
@@ -1,6 +1,5 @@
 package fj.data;
 
-import fj.Effect;
 import fj.F;
 import fj.F2;
 import fj.P;
@@ -683,9 +682,7 @@ public boolean exists(final F<A, Boolean> f) {
 
   @Override
   public boolean equals(Object o) {
-    return !
-            Equal.equalsValidationCheck(this, o) ? false :
-            Equal.arrayEqual(Equal.<A>anyEqual()).eq(this, (Array<A>) o);
+    return Equal.shallowEqualsO(this, o).orSome(P.lazy(u -> Equal.arrayEqual(Equal.<A>anyEqual()).eq(this, (Array<A>) o)));
   }
 
   /**

diff --git a/core/src/main/java/fj/data/Either.java b/core/src/main/java/fj/data/Either.java
@@ -80,8 +80,7 @@ public final <X> X either(final F<A, X> left, final F<B, X> right) {
   @Override
   public boolean equals(Object other) {
 
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.eitherEqual(Equal.<A>anyEqual(), Equal.<B>anyEqual()).eq(this, (Either<A, B>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.eitherEqual(Equal.<A>anyEqual(), Equal.<B>anyEqual()).eq(this, (Either<A, B>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/List.java b/core/src/main/java/fj/data/List.java
@@ -5,7 +5,6 @@
 import fj.Equal;
 import fj.F;
 import fj.F2;
-import fj.F3;
 import fj.Function;
 import fj.Hash;
 import fj.Monoid;
@@ -1818,8 +1817,7 @@ private void copy() {
         //Casting to List<A> here does not cause a runtime exception even if the type arguments don't match.
         //The cast is done to avoid the compiler warning "raw use of parameterized class 'List'"
 
-        return !Equal.equalsValidationCheck(this, obj) ? false :
-                Equal.listEqual(Equal.<A>anyEqual()).eq(this, (List<A>) obj);
+        return Equal.shallowEqualsO(this, obj).orSome(P.lazy(u -> Equal.listEqual(Equal.<A>anyEqual()).eq(this, (List<A>) obj)));
     }
 
     /**

diff --git a/core/src/main/java/fj/data/Option.java b/core/src/main/java/fj/data/Option.java
@@ -2,7 +2,6 @@
 
 import static fj.Bottom.error;
 
-import fj.Effect;
 import fj.F;
 import fj.F2;
 import fj.P;
@@ -33,7 +32,6 @@
 import static fj.data.Validation.parseLong;
 import static fj.data.Validation.parseShort;
 import static fj.Show.optionShow;
-import static fj.Show.anyShow;
 
 import java.util.Collection;
 import java.util.Iterator;
@@ -628,8 +626,7 @@ public final boolean exists(final F<A, Boolean> f) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.optionEqual(Equal.<A>anyEqual()).eq(this, (Option<A>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.optionEqual(Equal.<A>anyEqual()).eq(this, (Option<A>) other)));
   }
 
   /**

diff --git a/core/src/main/java/fj/data/Seq.java b/core/src/main/java/fj/data/Seq.java
@@ -48,8 +48,7 @@ public static <A> Seq<A> empty() {
   @Override
   public boolean equals(Object other) {
 
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.seqEqual(Equal.<A>anyEqual()).eq(this, (Seq<A>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.seqEqual(Equal.<A>anyEqual()).eq(this, (Seq<A>) other)));
   }
 
   /**

diff --git a/core/src/main/java/fj/data/Set.java b/core/src/main/java/fj/data/Set.java
@@ -142,7 +142,7 @@ public static <A> Set<A> empty(final Ord<A> ord) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false : Equal.setEqual(Equal.<A>anyEqual()).eq(this, (Set<A>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.setEqual(Equal.<A>anyEqual()).eq(this, (Set<A>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/Stream.java b/core/src/main/java/fj/data/Stream.java
@@ -1,12 +1,10 @@
 package fj.data;
 
-import fj.Effect;
 import fj.Equal;
 import fj.Hash;
 import fj.Show;
 import fj.F;
 import fj.F2;
-import fj.F3;
 import fj.Function;
 import fj.Monoid;
 import fj.Ord;
@@ -1239,8 +1237,7 @@ public final boolean forall(final F<A, Boolean> f) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.streamEqual(Equal.<A>anyEqual()).eq(this, (Stream<A>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.streamEqual(Equal.<A>anyEqual()).eq(this, (Stream<A>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/Tree.java b/core/src/main/java/fj/data/Tree.java
@@ -261,8 +261,7 @@ private Stream<String> drawTree(final Show<A> s) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.treeEqual(Equal.<A>anyEqual()).eq(this, (Tree<A>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.treeEqual(Equal.<A>anyEqual()).eq(this, (Tree<A>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/TreeMap.java b/core/src/main/java/fj/data/TreeMap.java
@@ -37,8 +37,7 @@ public static <K, V> TreeMap<K, V> empty(final Ord<K> keyOrd) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.treeMapEqual(Equal.<K>anyEqual(), Equal.<V>anyEqual()).eq(this, (TreeMap<K, V>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.treeMapEqual(Equal.<K>anyEqual(), Equal.<V>anyEqual()).eq(this, (TreeMap<K, V>) other)));
   }
 
   @Override

diff --git a/core/src/main/java/fj/data/Validation.java b/core/src/main/java/fj/data/Validation.java
@@ -251,8 +251,7 @@ public boolean exists(final F<T, Boolean> f) {
 
   @Override
   public boolean equals(Object other) {
-    return !Equal.equalsValidationCheck(this, other) ? false :
-            Equal.validationEqual(Equal.<E>anyEqual(), Equal.<T>anyEqual()).eq(this, (Validation<E, T>) other);
+    return Equal.shallowEqualsO(this, other).orSome(P.lazy(u -> Equal.validationEqual(Equal.<E>anyEqual(), Equal.<T>anyEqual()).eq(this, (Validation<E, T>) other)));
   }
 
   @Override

diff --git a/core/src/test/java/fj/data/ListTest.java b/core/src/test/java/fj/data/ListTest.java
@@ -16,9 +16,15 @@ public void objectMethods() {
 
         int max = 5;
         List<Integer> list = List.range(1, max);
+
+        assertTrue(list.equals(list));
         assertTrue(list.equals(List.range(1, max)));
+
         assertFalse(list.equals(List.single(1)));
         assertFalse(list.equals(true));
+        assertFalse(list.equals(null));
+
+
 
         assertTrue(List.list(1, 2).toString().equals("List(1,2)"));