2016 Update

2016-12-05 22:15:40 +01:00 · 2016-12-05 22:15:40 +01:00 · dcf5d15da3
commit dcf5d15da3
parent 948b86eafa
7965 changed files with 139854 additions and 31002 deletions
--- a/Task/24-game/Haskell/24-game.hs
+++ b/Task/24-game/Haskell/24-game.hs
@ -29,10 +29,9 @@ processGuess digits xs = calc xs >>= check
          check x  = Left (show (fromRational (x :: Rational)) ++ " is wrong")

 -- A Reverse Polish Notation calculator with full error handling
-calc = result []
-    where result [n] [] = Right n
-          result _   [] = Left "Too few operators"
-          result ns  (x:xs) = simplify ns x >>= flip result xs
+calc xs = foldM simplify [] xs >>= \ns -> (case ns of
+                                             [n] -> Right n
+                                             _   -> Left "Too few operators")

 simplify (a:b:ns) s | isOp s = Right ((fromJust $ lookup s ops) b a : ns)
 simplify _        s | isOp s = Left ("Too few values before " ++ s)