praxis

commit 93c1c0aa179fb8e13fcbe100a75168acc1c48fbf
parent 82d5dd058a01747770d46c8f38b083ef6d8f8695
Author: Jared Tobin <jared@jtobin.ca>
Date:   Tue, 26 Jun 2018 10:23:39 +1200

Overlapping thing.

Diffstat:
A
20180608_overlap/Overlap.hs
 | 
43
+++++++++++++++++++++++++++++++++++++++++++

1 file changed, 43 insertions(+), 0 deletions(-)
diff --git a/20180608_overlap/Overlap.hs b/20180608_overlap/Overlap.hs
@@ -0,0 +1,43 @@
+{-# OPTIONS_GHC -Wall #-}
+
+data Range = Range !Int !Int
+  deriving (Eq, Show)
+
+range :: Int -> Int -> Maybe Range
+range a b
+  | a <= b    = Just (Range a b)
+  | otherwise = Nothing
+
+overlap :: Range -> Range -> Maybe Range
+overlap (Range al bl) (Range ar br)
+  | bl < ar || br < al = Nothing
+  | otherwise          = range (max al ar) (min bl br)
+
+main :: IO ()
+main = do
+  let bar = do
+        r0 <- range 17 25
+        r1 <- range 12 19
+        overlap r0 r1
+
+      baz = do
+        r0 <- range 12 17
+        r1 <- range 19 25
+        overlap r0 r1
+
+      qux = do
+        r0 <- range 19 25
+        r1 <- range 12 17
+        overlap r0 r1
+
+      zap = do
+        r0 <- range 19 25
+        r1 <- range 22 30
+        overlap r0 r1
+
+  print bar
+  print baz
+  print qux
+  print zap
+
+