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authorJed Barber <jjbarber@y7mail.com>2012-09-28 00:46:11 +1000
committerJed Barber <jjbarber@y7mail.com>2012-09-28 00:46:11 +1000
commit02060edfb27d906035215f9afd0f1bf13838264c (patch)
tree631a56d51c54eba130c15a05eac6f04f69122e6d /Library
parent4146476e6fb7d07f13c29d3cc9ecf4addf2cbc99 (diff)
Type alpha equivalence in limbo
Diffstat (limited to 'Library')
-rw-r--r--Library/Term.hs14
-rw-r--r--Library/TypeVar.hs13
2 files changed, 19 insertions, 8 deletions
diff --git a/Library/Term.hs b/Library/Term.hs
index 4377047..814716f 100644
--- a/Library/Term.hs
+++ b/Library/Term.hs
@@ -38,8 +38,8 @@ type Substitution = ( [(Name,Type)], [(Var,Term)] )
instance Show Term where
- show (TVar a) = show a
- show (TConst a _) = show a
+ show (TVar a) = (show a)
+ show (TConst a _) = show a
show (TApp (TApp eq lhs) rhs)
| isEq eq = "(" ++ (show lhs) ++ " = " ++ (show rhs) ++ ")"
show (TApp a b) = "(" ++ (show a) ++ " " ++ (show b) ++ ")"
@@ -56,21 +56,21 @@ alphaEquiv a b =
let equiv = \term1 term2 varmap1 varmap2 depth ->
case (term1,term2) of
(TConst a1 b1, TConst a2 b2) ->
- a1 == a2 && b1 == b2
+ a1 == a2 --&& b1 == b2
(TApp a1 b1, TApp a2 b2) ->
equiv a1 a2 varmap1 varmap2 depth &&
equiv b1 b2 varmap1 varmap2 depth
(TAbs (TVar (Var name1 type1)) b1, TAbs (TVar (Var name2 type2)) b2) ->
- type1 == type2 &&
+ --type1 == type2 &&
equiv b1 b2 newmap1 newmap2 (depth+1)
where newmap1 = Map.insert (Var name1 type1) depth varmap1
newmap2 = Map.insert (Var name2 type2) depth varmap2
- (TVar a1, TVar a2) ->
- a1 == a2 && Map.notMember a1 varmap1 && Map.notMember a2 varmap2 ||
- Map.lookup a1 varmap1 == Map.lookup a2 varmap2
+ (TVar (Var name1 type1), TVar (Var name2 type2)) ->
+ (name1 == name2 && Map.notMember (Var name1 type1) varmap1 && Map.notMember (Var name2 type2) varmap2) ||
+ Map.lookup (Var name1 type1) varmap1 == Map.lookup (Var name2 type2) varmap2
(_,_) -> False
in equiv a b Map.empty Map.empty 0
diff --git a/Library/TypeVar.hs b/Library/TypeVar.hs
index 078d5d3..e8ce972 100644
--- a/Library/TypeVar.hs
+++ b/Library/TypeVar.hs
@@ -34,7 +34,7 @@ data TypeOp = TypeOp { tyOp :: Name } deriving (Eq, Ord)
data Type = TypeVar { typeVar :: Name }
| AType { aType :: [Type]
- , aTypeOp :: TypeOp } deriving (Eq, Ord)
+ , aTypeOp :: TypeOp } deriving (Ord)
data Const = Const { constName :: Name } deriving (Eq, Ord)
@@ -60,6 +60,17 @@ instance Show Var where
show (Var a _) = show a
+instance Eq Type where
+ a == b = a `typeAlphaEquiv` b
+
+
+
+typeAlphaEquiv :: Type -> Type -> Bool
+typeAlphaEquiv (TypeVar a) (TypeVar b) = True
+typeAlphaEquiv (AType alist aop) (AType blist bop) =
+ aop == bop && all (\(x,y) -> x == y) (zip alist blist)
+typeAlphaEquiv _ _ = True
+
mkEqualsType :: Type -> Type
mkEqualsType ty = typeFunc ty (typeFunc ty typeBool)