it inserts a label pair into list of list, which contains label pairs sharing the common label.
I run it with ghci -fglasglow-exts -fallow-undecidable-instances
*Test> ins a Nil
Cons (Cons (LAB A [],[]) Nil) Nil
*Test> ins a (ins a Nil)
Cons (Cons (LAB A [],[]) (Cons (LAB A [],[]) Nil)) Nil
*Test> ins b (ins a Nil)
Cons (Cons (LAB A [],[]) Nil) (Cons (Cons (LAB B [],[]) Nil) Nil)
*Test> ins a (ins b (ins a Nil))
Cons (Cons (LAB A [],[]) (Cons (LAB A [],[]) Nil)) (Cons (Cons (LAB B [],[]) Nil) Nil)
*Test> ins b (ins a (ins b (ins a Nil)))
ghc-6.2: panic! (the `impossible' happened, GHC version 6.2):
nameModule zddIns1 {- v a3rC -}
another trial:
*Test> ins b Nil Cons (Cons (LAB B [],[]) Nil) Nil *Test> ins a (ins b Nil) Cons (Cons (LAB B [],[]) Nil) (Cons (Cons (LAB A [],[]) Nil) Nil) *Test> ins b (ins a (ins b Nil)) ghc-6.2: panic! (the `impossible' happened, GHC version 6.2): nameModule zddIns1 {- v a5Ix -}
it seems whenever I insert label "b" into a list that contains list of "a" and list of "b", it pops into error.
Regards, Kenny LU Zhuo Ming
module Test where
data LAB l r = LAB l r deriving Show
data OR a b = OR a b deriving Show
data Cons x y = Cons x y deriving Show
data Nil = Nil deriving Show
data T = T
data F = F
data A = A deriving Show
data B = B deriving Show
data Zero = Zero
data Succ n = Succ n
a = ((LAB A []),[])
b = ((LAB B []),[])
-- insertion function
-- insert label pairs in the a list of list, each list contains a collection of
-- label pair that sharing the common label.
class Ins r l l' | r l -> l' where ins :: r -> l -> l'
instance Ins ((LAB l1 r1),r1') Nil (Cons (Cons ((LAB l1 r1),r1') Nil) Nil) where
ins l Nil = (Cons (Cons l Nil) Nil)
instance ( L2N l1 n1
, L2N l2 n2
, EqR n1 n2 b
, Ins1 ((LAB l1 r1),r1') (Cons (Cons ((LAB l2 r2),r2') rs) rs') b l
) => Ins ((LAB l1 r1),r1') (Cons (Cons ((LAB l2 r2),r2') rs) rs') l where
ins ((LAB l1 r1),r1') (Cons (Cons ((LAB l2 r2),r2') rs) rs') = ins1 ((LAB l1 r1),r1') (Cons (Cons ((LAB l2 r2),r2') rs) rs') (eqR (l2n l1) (l2n l2))
class Ins1 r l b l' | r l b -> l' where ins1 :: r -> l -> b -> l'
instance Ins1 ((LAB l1 r1),r1') (Cons r rs) T (Cons (Cons ((LAB l1 r1),r1') r) rs) where
ins1 l (Cons r rs) _ = (Cons (Cons l r) rs)
instance ( Ins ((LAB l1 r1),r1') rs rs'
) => Ins1 ((LAB l1 r1),r1') (Cons r rs) F (Cons r rs') where
ins1 l (Cons r rs) _ = (Cons r (ins l rs))-- class for mapping label to number
class L2N l n | l -> n where l2n :: l -> n
instance L2N A Zero where l2n A = Zero
instance L2N B (Succ Zero) where l2n B = Succ Zero
-- class for comparing number type
class EqR n1 n2 b | n1 n2 -> b where eqR :: n1 -> n2 -> b
instance EqR Zero Zero T where eqR _ _ = T
instance EqR Zero (Succ n) F where eqR _ _ = F
instance EqR (Succ n) Zero F where eqR _ _ = F
instance (EqR n1 n2 b) => EqR (Succ n1) (Succ n2) b where eqR (Succ n1) (Succ n2) = eqR n1 n
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