From 9d9677e0a34d412fed209996fde4ad0ae6acd463 Mon Sep 17 00:00:00 2001
From: bculkin2442 <bjculkin@mix.wvu.edu>
Date: Tue, 10 May 2016 17:37:31 -0400
Subject: Added ability to bimap over pairs and pair like things

---
 .../java/bjc/utils/funcdata/theory/Bifunctor.java  | 41 ++++++++++++++++++++++
 1 file changed, 41 insertions(+)

(limited to 'BJC-Utils2/src/main/java/bjc/utils/funcdata/theory')

diff --git a/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java
index 3bea135..e8c74fc 100644
--- a/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java
+++ b/BJC-Utils2/src/main/java/bjc/utils/funcdata/theory/Bifunctor.java
@@ -50,6 +50,47 @@ public interface Bifunctor<LeftType, RightType> {
 			Function<Bifunctor<OldLeft, OldRight>, Bifunctor<OldLeft, NewRight>>
 			fmapRight(Function<OldRight, NewRight> func);
 
+	/**
+	 * Lift a pair of functions to a single function that maps over both
+	 * parts of a pair
+	 * 
+	 * @param <OldLeft>
+	 *            The old left type of the pair
+	 * @param <OldRight>
+	 *            The old right type of the pair
+	 * @param <NewLeft>
+	 *            The new left type of the pair
+	 * @param <NewRight>
+	 *            The new right type of the pair
+	 * @param leftFunc
+	 *            The function that maps over the left of the pair
+	 * @param rightFunc
+	 *            The function that maps over the right of the pair
+	 * @return A function that maps over both parts of the pair
+	 */
+	public default <OldLeft, OldRight, NewLeft, NewRight>
+			Function<Bifunctor<OldLeft, OldRight>, Bifunctor<NewLeft, NewRight>>
+			bimap(Function<OldLeft, NewLeft> leftFunc,
+					Function<OldRight, NewRight> rightFunc) {
+		Function<Bifunctor<OldLeft, OldRight>, Bifunctor<NewLeft, NewRight>> bimappedFunc =
+				(argPair) -> {
+					Function<Bifunctor<OldLeft, OldRight>, Bifunctor<NewLeft, OldRight>> leftMapper =
+							argPair.<OldLeft, OldRight, NewLeft> fmapLeft(
+									leftFunc);
+
+					Bifunctor<NewLeft, OldRight> leftMappedFunctor =
+							leftMapper.apply(argPair);
+					Function<Bifunctor<NewLeft, OldRight>, Bifunctor<NewLeft, NewRight>> rightMapper =
+							leftMappedFunctor
+									.<NewLeft, OldRight, NewRight> fmapRight(
+											rightFunc);
+
+					return rightMapper.apply(leftMappedFunctor);
+				};
+
+		return bimappedFunc;
+	}
+
 	/**
 	 * Get the value contained on the left of this bifunctor
 	 * 
-- 
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