{- |

Module : $Header$

Description : choose a minimal type for overloaded terms

Copyright : (c) Christian Maeder and Uni Bremen 2003

License : similar to LGPL, see HetCATS/LICENSE.txt or LIZENZ.txt

Maintainer : Christian.Maeder@dfki.de

Stability : experimental

Portability : portable

choose a minimal type

-}

module HasCASL.MinType where

import HasCASL.As

import HasCASL.TypeAna

q2p :: (a, b, c, d) -> (c, d)

q2p (_, _, c, d) = (c,d)

typeNub :: TypeEnv -> (a -> (Type, Term)) -> [a] -> [a]

typeNub te f l = case l of

[] -> []

x : xs -> if any (flip comp (f x) . f) xs then typeNub te f xs

else x : typeNub te f (filter (not . comp (f x) . f) xs)

where

comp :: (Type, Term) -> (Type, Term) -> Bool

comp (ty1, t1) (ty2, t2) = eqTerm t1 t2 &&

lesserType te ty1 ty2

eqTerm :: Term -> Term -> Bool

eqTerm t1 t2 = case (t1, t2) of

(TypedTerm t _ _ _, _) -> eqTerm t t2

(_, TypedTerm t _ _ _) -> eqTerm t1 t

(QualVar (VarDecl v1 _s1 _ _), QualVar (VarDecl v2 _s2 _ _)) ->

v1 == v2

(QualOp _ i1 _ _ _, QualOp _ i2 _ _ _) -> i1 == i2

(ApplTerm tf1 ta1 _, ApplTerm tf2 ta2 _) ->

eqTerm tf1 tf2 && eqTerm ta1 ta2

(TupleTerm ts1 _, TupleTerm ts2 _) ->

length ts1 == length ts2 && and (zipWith eqTerm ts1 ts2)

(QuantifiedTerm q1 vs1 f1 _, QuantifiedTerm q2 vs2 f2 _) ->

(q1, vs1) == (q2, vs2) && eqTerm f1 f2

(LambdaTerm ps1 p1 f1 _, LambdaTerm ps2 p2 f2 _) ->

and (zipWith eqTerm ps1 ps2) && p1 == p2 && eqTerm f1 f2

&& length ps1 == length ps2

(CaseTerm f1 e1 _, CaseTerm f2 e2 _) ->

eqTerm f1 f2 && length e1 == length e2 && and (zipWith eqProgEq e1 e2)

(LetTerm _ e1 f1 _, LetTerm _ e2 f2 _) ->

eqTerm f1 f2 && length e1 == length e2 && and (zipWith eqProgEq e1 e2)

_ -> False

eqProgEq :: ProgEq -> ProgEq -> Bool

eqProgEq (ProgEq p1 t1 _) (ProgEq p2 t2 _) = eqTerm p1 p2 && eqTerm t1 t2