Add min and max Semigroup instances for Ords

puffnfresh · puffnfresh · commit e3bf1253bfc7 · 2016-05-26T16:00:02.000+10:00
diff --git a/core/src/main/java/fj/Ord.java b/core/src/main/java/fj/Ord.java
@@ -15,6 +15,7 @@
 import java.util.Comparator;
 
 import static fj.Function.curry;
+import static fj.Semigroup.semigroup;
 
 /**
  * Tests for ordering between two objects.
@@ -157,7 +158,15 @@ public A min(final A a1, final A a2) {
    */
   public final F<A, F<A, A>> min = curry(this::min);
 
-  public Ord<A> reverse() { return ord(Function.flip(f)); }
+  public final Semigroup<A> minSemigroup() {
+      return semigroup(this::min);
+  }
+
+  public final Semigroup<A> maxSemigroup() {
+      return semigroup(this::max);
+  }
+
+  public final Ord<A> reverse() { return ord(Function.flip(f)); }
 
   /**
    * Returns an order instance that uses the given equality test and ordering function.
diff --git a/core/src/main/java/fj/Semigroup.java b/core/src/main/java/fj/Semigroup.java
@@ -147,12 +147,12 @@ public static <A> Semigroup<A> semigroup(final F2<A, A, A> sum) {
   /**
    * A semigroup that yields the maximum of integers.
    */
-  public static final Semigroup<Integer> intMaximumSemigroup = semigroup(Ord.intOrd.max);
+  public static final Semigroup<Integer> intMaximumSemigroup = Ord.intOrd.maxSemigroup();
 
   /**
    * A semigroup that yields the minimum of integers.
    */
-  public static final Semigroup<Integer> intMinimumSemigroup = semigroup(Ord.intOrd.min);
+  public static final Semigroup<Integer> intMinimumSemigroup = Ord.intOrd.minSemigroup();
 
   /**
    * A semigroup that adds big integers.
@@ -169,12 +169,12 @@ public static <A> Semigroup<A> semigroup(final F2<A, A, A> sum) {
   /**
    * A semigroup that yields the maximum of big integers.
    */
-  public static final Semigroup<BigInteger> bigintMaximumSemigroup = semigroup(Ord.bigintOrd.max);
+  public static final Semigroup<BigInteger> bigintMaximumSemigroup = Ord.bigintOrd.maxSemigroup();
 
   /**
    * A semigroup that yields the minimum of big integers.
    */
-  public static final Semigroup<BigInteger> bigintMinimumSemigroup = semigroup(Ord.bigintOrd.min);
+  public static final Semigroup<BigInteger> bigintMinimumSemigroup = Ord.bigintOrd.minSemigroup();
 
   /**
    * A semigroup that adds big decimals.
@@ -191,12 +191,12 @@ public static <A> Semigroup<A> semigroup(final F2<A, A, A> sum) {
   /**
    * A semigroup that yields the maximum of big decimals.
    */
-  public static final Semigroup<BigDecimal> bigDecimalMaximumSemigroup = semigroup(Ord.bigdecimalOrd.max);
+  public static final Semigroup<BigDecimal> bigDecimalMaximumSemigroup = Ord.bigdecimalOrd.maxSemigroup();
 
   /**
    * A semigroup that yields the minimum of big decimals.
    */
-  public static final Semigroup<BigDecimal> bigDecimalMinimumSemigroup = semigroup(Ord.bigdecimalOrd.min);
+  public static final Semigroup<BigDecimal> bigDecimalMinimumSemigroup = Ord.bigdecimalOrd.minSemigroup();
 
   /**
    * A semigroup that multiplies natural numbers.
@@ -213,12 +213,12 @@ public static <A> Semigroup<A> semigroup(final F2<A, A, A> sum) {
   /**
    * A semigroup that yields the maximum of natural numbers.
    */
-  public static final Semigroup<Natural> naturalMaximumSemigroup = semigroup(Ord.naturalOrd.max);
+  public static final Semigroup<Natural> naturalMaximumSemigroup = Ord.naturalOrd.maxSemigroup();
 
   /**
    * A semigroup that yields the minimum of natural numbers.
    */
-  public static final Semigroup<Natural> naturalMinimumSemigroup = semigroup(Ord.naturalOrd.min);
+  public static final Semigroup<Natural> naturalMinimumSemigroup = Ord.naturalOrd.minSemigroup();
 
   /**
    * A semigroup that adds longs.
@@ -233,12 +233,12 @@ public static <A> Semigroup<A> semigroup(final F2<A, A, A> sum) {
   /**
    * A semigroup that yields the maximum of longs.
    */
-  public static final Semigroup<Long> longMaximumSemigroup = semigroup(Ord.longOrd.max);
+  public static final Semigroup<Long> longMaximumSemigroup = Ord.longOrd.maxSemigroup();
 
   /**
    * A semigroup that yields the minimum of longs.
    */
-  public static final Semigroup<Long> longMinimumSemigroup = semigroup(Ord.longOrd.min);
+  public static final Semigroup<Long> longMinimumSemigroup = Ord.longOrd.minSemigroup();
 
   /**
    * A semigroup that ORs booleans.
