{-# LANGUAGE DatatypeContexts #-}
data SREG = RIP
data DREG = RBX
data SNDREG = RAX
data (Source s, Destination d) => Instruction s d = MOV s d
class Source a
class Destination a
instance Source SREG
instance Source SNDREG
instance Destination DREG
instance Destination SNDREG
move :: (Source s, Destination d) => s -> d -> Instruction s d
move s d = MOV s d
hello = [move RAX RAX, move RAX RAX]
hello = [move RAX RAX, move RAX RBX] -- this is still not allowed.