adding Tuple2/3/4#into

jnape · jnape · commit bd49839a1db8 · 2017-01-08T13:42:14.000-06:00
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple2.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple2.java
@@ -5,6 +5,7 @@
 import com.jnape.palatable.lambda.functor.Functor;
 
 import java.util.Map;
+import java.util.function.BiFunction;
 import java.util.function.Function;
 
 /**
@@ -52,6 +53,18 @@ public _2 _2() {
         return _2;
     }
 
+    /**
+     * Destructure and apply this tuple to a function accepting the same number of arguments as this tuple's
+     * slots. This can be thought of as a kind of dual to uncurrying a function and applying a tuple to it.
+     *
+     * @param fn the function to apply
+     * @param <R>        the return type of the function
+     * @return the result of applying the destructured tuple to the function
+     */
+    public <R> R into(BiFunction<? super _1, ? super _2, ? extends R> fn) {
+        return fn.apply(_1, _2);
+    }
+
     @Override
     public _1 getKey() {
         return _1();
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple3.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple3.java
@@ -1,6 +1,7 @@
 package com.jnape.palatable.lambda.adt.hlist;
 
 import com.jnape.palatable.lambda.adt.hlist.HList.HCons;
+import com.jnape.palatable.lambda.functions.Fn3;
 import com.jnape.palatable.lambda.functor.Bifunctor;
 import com.jnape.palatable.lambda.functor.Functor;
 
@@ -62,6 +63,19 @@ public _3 _3() {
         return _3;
     }
 
+    /**
+     * Destructure and apply this tuple to a function accepting the same number of arguments as this tuple's
+     * slots.
+     *
+     * @param fn  the function to apply
+     * @param <R> the return type of the function
+     * @return the result of applying the destructured tuple to the function
+     * @see Tuple2#into
+     */
+    public <R> R into(Fn3<? super _1, ? super _2, ? super _3, ? extends R> fn) {
+        return fn.apply(_1, _2, _3);
+    }
+
     @Override
     public <_3Prime> Tuple3<_1, _2, _3Prime> fmap(Function<? super _3, ? extends _3Prime> fn) {
         return biMapR(fn);
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple4.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple4.java
@@ -1,6 +1,7 @@
 package com.jnape.palatable.lambda.adt.hlist;
 
 import com.jnape.palatable.lambda.adt.hlist.HList.HCons;
+import com.jnape.palatable.lambda.functions.Fn4;
 import com.jnape.palatable.lambda.functor.Bifunctor;
 import com.jnape.palatable.lambda.functor.Functor;
 
@@ -74,6 +75,19 @@ public _4 _4() {
         return _4;
     }
 
+    /**
+     * Destructure and apply this tuple to a function accepting the same number of arguments as this tuple's
+     * slots.
+     *
+     * @param fn  the function to apply
+     * @param <R> the return type of the function
+     * @return the result of applying the destructured tuple to the function
+     * @see Tuple2#into
+     */
+    public <R> R into(Fn4<? super _1, ? super _2, ? super _3, ? super _4, ? extends R> fn) {
+        return fn.apply(_1, _2, _3, _4);
+    }
+
     @Override
     public <_4Prime> Tuple4<_1, _2, _3, _4Prime> fmap(Function<? super _4, ? extends _4Prime> fn) {
         return biMapR(fn);
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple2Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple2Test.java
@@ -55,6 +55,12 @@ public void randomAccess() {
         verifyNoMoreInteractions(spiedTail);
     }
 
+    @Test
+    public void into() {
+        Tuple2<String, Integer> tuple = tuple("foo", 1);
+        assertEquals("foo1", tuple.into((s, i) -> s + i));
+    }
+
     @Test
     public void functorProperties() {
         assertEquals(new Tuple2<>(1, new SingletonHList<>("2")), tuple2.fmap(Object::toString));
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple3Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple3Test.java
@@ -54,6 +54,12 @@ public void randomAccess() {
         verifyNoMoreInteractions(spiedTail);
     }
 
+    @Test
+    public void into() {
+        Tuple3<String, Integer, Double> tuple = tuple("foo", 1, 2.0d);
+        assertEquals("foo12.0", tuple.into((s, i, d) -> s + i + d));
+    }
+
     @Test
     public void functorProperties() {
         assertEquals(new Tuple3<>(1, new Tuple2<>("2", new SingletonHList<>("3"))), tuple3.fmap(Object::toString));
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple4Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple4Test.java
@@ -57,6 +57,12 @@ public void randomAccess() {
         verifyNoMoreInteractions(spiedTail);
     }
 
+    @Test
+    public void into() {
+        Tuple4<String, Integer, Double, Boolean> tuple = tuple("foo", 1, 2.0d, false);
+        assertEquals("foo12.0false", tuple.into((s, i, d, b) -> s + i + d + b));
+    }
+
     @Test
     public void functorProperties() {
         assertEquals(new Tuple4<>(1, new Tuple3<>("2", new Tuple2<>('3', new SingletonHList<>(true)))), tuple4.fmap(x -> !x));
