Adding into, used for applying a destructured tuple to a bifunction

jnape · jnape · commit 920229033dca · 2017-10-08T14:25:36.000-05:00
diff --git a/src/main/java/com/jnape/palatable/lambda/functions/builtin/fn2/Into.java b/src/main/java/com/jnape/palatable/lambda/functions/builtin/fn2/Into.java
@@ -0,0 +1,41 @@
+package com.jnape.palatable.lambda.functions.builtin.fn2;
+
+import com.jnape.palatable.lambda.adt.hlist.Tuple2;
+import com.jnape.palatable.lambda.functions.Fn1;
+import com.jnape.palatable.lambda.functions.Fn2;
+
+import java.util.function.BiFunction;
+
+/**
+ * Given a <code>{@link BiFunction}&lt;A, B, C&gt;</code> and a <code>{@link Tuple2}&lt;A, B&gt;</code>, destructure the
+ * tuple and apply the slots as arguments to the function, returning the result.
+ *
+ * @param <A> the first argument type
+ * @param <B> the second argument type
+ * @param <C> the result type
+ */
+public final class Into<A, B, C> implements Fn2<BiFunction<? super A, ? super B, ? extends C>, Tuple2<A, B>, C> {
+
+    private static final Into INSTANCE = new Into();
+
+    private Into() {
+    }
+
+    @Override
+    public C apply(BiFunction<? super A, ? super B, ? extends C> fn, Tuple2<A, B> tuple) {
+        return tuple.into(fn);
+    }
+
+    @SuppressWarnings("unchecked")
+    public static <A, B, C> Into<A, B, C> into() {
+        return INSTANCE;
+    }
+
+    public static <A, B, C> Fn1<Tuple2<A, B>, C> into(BiFunction<? super A, ? super B, ? extends C> fn) {
+        return Into.<A, B, C>into().apply(fn);
+    }
+
+    public static <A, B, C> C into(BiFunction<? super A, ? super B, ? extends C> fn, Tuple2<A, B> tuple) {
+        return Into.<A, B, C>into(fn).apply(tuple);
+    }
+}
diff --git a/src/test/java/com/jnape/palatable/lambda/functions/builtin/fn2/IntoTest.java b/src/test/java/com/jnape/palatable/lambda/functions/builtin/fn2/IntoTest.java
@@ -0,0 +1,15 @@
+package com.jnape.palatable.lambda.functions.builtin.fn2;
+
+import org.junit.Test;
+
+import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
+import static com.jnape.palatable.lambda.functions.builtin.fn2.Into.into;
+import static org.junit.Assert.assertEquals;
+
+public class IntoTest {
+
+    @Test
+    public void appliesTupleToFunction() {
+        assertEquals((Integer) 3, into((a, b) -> a + b, tuple(1, 2)));
+    }
+}
