Present is a singleton

jnape · jnape · commit fdcadccbde4a · 2018-05-03T18:59:07.000-05:00
diff --git a/src/main/java/com/jnape/palatable/lambda/monoid/builtin/Present.java b/src/main/java/com/jnape/palatable/lambda/monoid/builtin/Present.java
@@ -27,6 +27,8 @@
  */
 public final class Present<A> implements MonoidFactory<Semigroup<A>, Maybe<A>> {
 
+    private static final Present INSTANCE = new Present<>();
+
     private Present() {
     }
 
@@ -36,8 +38,9 @@ public Monoid<Maybe<A>> apply(Semigroup<A> aSemigroup) {
                       nothing());
     }
 
+    @SuppressWarnings("unchecked")
     public static <A> Present<A> present() {
-        return new Present<>();
+        return INSTANCE;
     }
 
     public static <A> Monoid<Maybe<A>> present(Semigroup<A> semigroup) {

Original file line number	Diff line number	Diff line change
`@@ -27,6 +27,8 @@`
`27`	`27`	`*/`
`28`	`28`	`public final class Present<A> implements MonoidFactory<Semigroup<A>, Maybe<A>> {`
`29`	`29`
	`30`	`+ private static final Present INSTANCE = new Present<>();`
	`31`	`+`
`30`	`32`	`private Present() {`
`31`	`33`	`}`
`32`	`34`
`@@ -36,8 +38,9 @@ public Monoid<Maybe<A>> apply(Semigroup<A> aSemigroup) {`
`36`	`38`	`nothing());`
`37`	`39`	`}`
`38`	`40`
	`41`	`+ @SuppressWarnings("unchecked")`
`39`	`42`	`public static <A> Present<A> present() {`
`40`		`- return new Present<>();`
	`43`	`+ return INSTANCE;`
`41`	`44`	`}`
`42`	`45`
`43`	`46`	`public static <A> Monoid<Maybe<A>> present(Semigroup<A> semigroup) {`