From af1b2b877b612d6125bea9f00bdd5c44fe3fe850 Mon Sep 17 00:00:00 2001
From: Ivan Malison <IvanMalison@gmail.com>
Date: Fri, 23 Mar 2018 21:25:09 -0700
Subject: [PATCH] Add knightDeltas.hs

---
 dotfiles/lib/bin/knightDeltas.hs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100755 dotfiles/lib/bin/knightDeltas.hs

diff --git a/dotfiles/lib/bin/knightDeltas.hs b/dotfiles/lib/bin/knightDeltas.hs
new file mode 100755
index 00000000..196d53d3
--- /dev/null
+++ b/dotfiles/lib/bin/knightDeltas.hs
@@ -0,0 +1,22 @@
+#!/usr/bin/env run_haskell_stack.sh
+
+import Data.Bifunctor
+import Data.Tuple
+
+knightDeltasSimple =
+  applyAll [swap] (1, 2)
+  >>= applyAll [first negate, second negate, bimapBoth negate]
+  where applyAll fns v = map ($ v) $ id:fns
+        bimapBoth fn = bimap fn fn
+
+knightDeltas = applyInStages [(1, 2)]
+               [ [swap]
+               , [bimapBoth (* 2)]
+               , [first negate, second negate, bimapBoth negate]
+               ]
+  where applyAll fns v = map ($ v) $ id:fns
+        applyAllToValues values fns = values >>= applyAll fns
+        applyInStages = foldl applyAllToValues
+        bimapBoth fn = bimap fn fn
+
+main = print knightDeltas