Making Over/Set/View use singleton instances; adding test for TypeSafeKey

jnape · jnape · commit 187ac4ef8d45 · 2017-01-27T22:52:38.000-06:00
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hmap/TypeSafeKey.java b/src/main/java/com/jnape/palatable/lambda/adt/hmap/TypeSafeKey.java
@@ -10,7 +10,6 @@
  *
  * @param <T> The type of the value that this key maps to inside an HMap
  */
-@SuppressWarnings("unused")
 public interface TypeSafeKey<T> {
 
     /**
diff --git a/src/main/java/com/jnape/palatable/lambda/lens/functions/Over.java b/src/main/java/com/jnape/palatable/lambda/lens/functions/Over.java
@@ -25,6 +25,8 @@
  */
 public final class Over<S, T, A, B> implements Fn3<Lens<S, T, A, B>, Function<? super A, ? extends B>, S, T> {
 
+    private static final Over INSTANCE = new Over();
+
     private Over() {
     }
 
@@ -35,8 +37,9 @@ public T apply(Lens<S, T, A, B> lens, Function<? super A, ? extends B> fn, S s)
                 .runIdentity();
     }
 
+    @SuppressWarnings("unchecked")
     public static <S, T, A, B> Over<S, T, A, B> over() {
-        return new Over<>();
+        return (Over<S, T, A, B>) INSTANCE;
     }
 
     public static <S, T, A, B> Fn2<Function<? super A, ? extends B>, S, T> over(
diff --git a/src/main/java/com/jnape/palatable/lambda/lens/functions/Set.java b/src/main/java/com/jnape/palatable/lambda/lens/functions/Set.java
@@ -25,6 +25,8 @@
  */
 public final class Set<S, T, A, B> implements Fn3<Lens<S, T, A, B>, B, S, T> {
 
+    private static final Set INSTANCE = new Set();
+
     private Set() {
     }
 
@@ -33,8 +35,9 @@ public T apply(Lens<S, T, A, B> lens, B b, S s) {
         return over(lens, constantly(b), s);
     }
 
+    @SuppressWarnings("unchecked")
     public static <S, T, A, B> Set<S, T, A, B> set() {
-        return new Set<>();
+        return INSTANCE;
     }
 
     public static <S, T, A, B> Fn2<B, S, T> set(Lens<S, T, A, B> lens) {
diff --git a/src/main/java/com/jnape/palatable/lambda/lens/functions/View.java b/src/main/java/com/jnape/palatable/lambda/lens/functions/View.java
@@ -20,6 +20,8 @@
  */
 public final class View<S, T, A, B> implements Fn2<Lens<S, T, A, B>, S, A> {
 
+    private static final View INSTANCE = new View();
+
     private View() {
     }
 
@@ -28,8 +30,9 @@ public A apply(Lens<S, T, A, B> lens, S s) {
         return lens.<Const<A, T>, Const<A, B>>fix().apply(Const::new, s).runConst();
     }
 
+    @SuppressWarnings("unchecked")
     public static <S, T, A, B> View<S, T, A, B> view() {
-        return new View<>();
+        return INSTANCE;
     }
 
     public static <S, T, A, B> Fn1<S, A> view(Lens<S, T, A, B> lens) {
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hmap/TypeSafeKeyTest.java b/src/test/java/com/jnape/palatable/lambda/adt/hmap/TypeSafeKeyTest.java
@@ -0,0 +1,14 @@
+package com.jnape.palatable.lambda.adt.hmap;
+
+import org.junit.Test;
+
+import static com.jnape.palatable.lambda.adt.hmap.TypeSafeKey.typeSafeKey;
+import static org.junit.Assert.assertFalse;
+
+public class TypeSafeKeyTest {
+
+    @Test
+    public void usesReferenceEquality() {
+        assertFalse(typeSafeKey().equals(typeSafeKey()));
+    }
+}

Original file line number	Diff line number	Diff line change
`@@ -10,7 +10,6 @@`
`10`	`10`	`*`
`11`	`11`	`* @param <T> The type of the value that this key maps to inside an HMap`
`12`	`12`	`*/`
`13`		`-@SuppressWarnings("unused")`
`14`	`13`	`public interface TypeSafeKey<T> {`
`15`	`14`
`16`	`15`	`/**`
Original file line number	Diff line number	Diff line change
`@@ -25,6 +25,8 @@`
`25`	`25`	`*/`
`26`	`26`	`public final class Over<S, T, A, B> implements Fn3<Lens<S, T, A, B>, Function<? super A, ? extends B>, S, T> {`
`27`	`27`
	`28`	`+ private static final Over INSTANCE = new Over();`
	`29`	`+`
`28`	`30`	`private Over() {`
`29`	`31`	`}`
`30`	`32`
`@@ -35,8 +37,9 @@ public T apply(Lens<S, T, A, B> lens, Function<? super A, ? extends B> fn, S s)`
`35`	`37`	`.runIdentity();`
`36`	`38`	`}`
`37`	`39`
	`40`	`+ @SuppressWarnings("unchecked")`
`38`	`41`	`public static <S, T, A, B> Over<S, T, A, B> over() {`
`39`		`- return new Over<>();`
	`42`	`+ return (Over<S, T, A, B>) INSTANCE;`
`40`	`43`	`}`
`41`	`44`
`42`	`45`	`public static <S, T, A, B> Fn2<Function<? super A, ? extends B>, S, T> over(`
Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,8 @@`
`20`	`20`	`*/`
`21`	`21`	`public final class View<S, T, A, B> implements Fn2<Lens<S, T, A, B>, S, A> {`
`22`	`22`
	`23`	`+ private static final View INSTANCE = new View();`
	`24`	`+`
`23`	`25`	`private View() {`
`24`	`26`	`}`
`25`	`27`
`@@ -28,8 +30,9 @@ public A apply(Lens<S, T, A, B> lens, S s) {`
`28`	`30`	`return lens.<Const<A, T>, Const<A, B>>fix().apply(Const::new, s).runConst();`
`29`	`31`	`}`
`30`	`32`
	`33`	`+ @SuppressWarnings("unchecked")`
`31`	`34`	`public static <S, T, A, B> View<S, T, A, B> view() {`
`32`		`- return new View<>();`
	`35`	`+ return INSTANCE;`
`33`	`36`	`}`
`34`	`37`
`35`	`38`	`public static <S, T, A, B> Fn1<S, A> view(Lens<S, T, A, B> lens) {`