Try this:
module Cycle (Cyclic(..)) where
import System.Time import Data.Word import Data.Int
class (Eq c,Enum c, Bounded c) => Cyclic c where cyclePeriod :: c -> Int cyclePeriod _ = fromEnum (maxBound :: c) - fromEnum (minBound :: c) + 1 succCycle :: c -> c succCycle c | c == maxBound = minBound | otherwise = succ c predCycle :: c-> c predCycle c | c == minBound = maxBound | otherwise = pred c fromCycle :: c -> Int fromCycle = fromEnum toCycle :: Int -> c toCycle = toEnum . (`mod` (cyclePeriod (undefined::c))) cycleFrom :: c -> [c] cycleFrom x = map toCycle [fromCycle x ..] cycleFromTo :: c -> c -> [c] cycleFromTo x y = let xi = fromCycle x yi = fromCycle y zi = if xi > yi then yi + cyclePeriod (undefined::c) else yi in map toCycle [xi .. zi] cycleFromThen :: c -> c -> [c] cycleFromThen x y = let xi = fromCycle x yi = fromCycle y in map toCycle [xi, yi ..] cycleFromThenTo :: c -> c -> c -> [c] cycleFromThenTo x y z = let c = cyclePeriod (undefined::c) xi = fromCycle x; yi = fromCycle y; zi = fromCycle z zi' = if xi <= yi then if yi <= zi then zi else zi + c else if zi <= yi then zi else zi - c in map toCycle [xi, yi .. zi']
instance Cyclic Day instance Cyclic Month instance Cyclic Bool instance Cyclic () instance Cyclic Ordering instance Cyclic Int instance Cyclic Char instance Cyclic Int8 -- Imported from GHC.Int instance Cyclic Int64 -- Imported from GHC.Int instance Cyclic Int32 -- Imported from GHC.Int instance Cyclic Int16 -- Imported from GHC.Int instance Cyclic Word8 -- Imported from GHC.Word instance Cyclic Word64 -- Imported from GHC.Word instance Cyclic Word32 -- Imported from GHC.Word instance Cyclic Word16 -- Imported from GHC.Word