signAnalysis

scripts/signAnalysis.hs

@@ -1,4 +1,6 @@
+{-# LANGUAGE FlexibleContexts #-}
 import qualified Algebra.Absolute as AlgAbs
+import qualified Algebra.Additive as AlgAdd
 import qualified Algebra.Ring     as AlgRing
 
 runLengthEncoding :: Eq a => [a] -> [(a,Int)]
@@ -9,8 +11,8 @@ runLengthEncoding = foldr code []
       | c == x        = (x,n+1):ts
       | otherwise     = (c,1):(x,n):ts
 
-signPermancesAndVariations :: (Eq a, AlgRing.C a, AlgAbs.C a) -> [a] -> (Int, Int)
-signPermancesAndVariations as = (permances, variations)
+signPermancesAndVariations :: (Eq a, AlgRing.C a, AlgAbs.C a) => [a] -> (Int, Int)
+signPermancesAndVariations as = (permanences, variations)
   where
     sign a = if AlgAbs.signum a == AlgRing.one then '+' else '-'
     signs = map sign as
@@ -20,15 +22,16 @@ signPermancesAndVariations as = (permances, variations)
     permanences = sum lengths - l
     variations = l - 1
 
-signVariations' :: (Eq a, AlgRing.C a, AlgAbs.C a) -> [a] -> Int
+signVariations' :: forall a. (Eq a, AlgRing.C a, AlgAbs.C a) => [a] -> Int
 signVariations' as = v1 + v2 + 2*v3
   where
     count x xs = sum (map (fromEnum . (== x)) xs)
     l = length as
-    sign a = case AlgAbs.signum a of
-      AlgRing.zero -> '0'
-      AlgRing.one  -> '+'
-      _            -> '-' 
+    sign :: a -> Char
+    sign a
+      | AlgAbs.signum a == AlgAdd.zero = '0'
+      | AlgAbs.signum a == AlgRing.one = '+'
+      | otherwise                      = '-' 
     signs = map sign as
     chunks2 = [(signs !! i, signs !! (i+1)) | i <- [0 .. l-2]]
     v1 = count ('+', '-') chunks2