all tasks

Task/Short-circuit-evaluation/Haskell/short-circuit-evaluation-1.hs

@@ -0,0 +1,18 @@
+module ShortCircuit where
+
+import Prelude hiding ((&&), (||))
+import Debug.Trace
+
+False && _     = False
+True  && False = False
+_     && _     = True
+
+True  || _     = True
+False || True  = True
+_     || _     = False
+
+a p = trace ("<a " ++ show p ++ ">") p
+b p = trace ("<b " ++ show p ++ ">") p
+
+main = mapM_ print (    [ a p || b q | p <- [False, True], q <- [False, True] ]
+                     ++ [ a p && b q | p <- [False, True], q <- [False, True] ])

Task/Short-circuit-evaluation/Haskell/short-circuit-evaluation-2.hs

@@ -0,0 +1,7 @@
+_     && False = False
+False && True  = False
+_     && _     = True
+
+_     || True  = True
+True  || False = True
+_     || _     = False

Task/Short-circuit-evaluation/Haskell/short-circuit-evaluation-3.hs

@@ -0,0 +1,11 @@
+p && q = case p of
+           False -> False
+           _     -> case q of
+                      False -> False
+                      _     -> True
+
+p || q = case p of
+           True -> True
+           _    -> case q of
+                      True -> True
+                      _    -> False