\begin{code}
module HsTypes (
HsType(..), MonoUsageAnn(..), HsTyVar(..),
- Context, ClassAssertion
+ HsContext, HsClassAssertion, HsPred(..)
, mkHsForAllTy, mkHsUsForAllTy
, getTyVarName, replaceTyVarName
, pprParendHsType
- , pprForAll, pprContext, pprClassAssertion
- , cmpHsType, cmpHsTypes, cmpContext
+ , pprForAll, pprHsContext, pprHsClassAssertion, pprHsPred
+ , cmpHsType, cmpHsTypes, cmpHsContext, cmpHsPred
) where
#include "HsVersions.h"
This is the syntax for types as seen in type signatures.
\begin{code}
-type Context name = [ClassAssertion name]
-
-type ClassAssertion name = (name, [HsType name])
- -- The type is usually a type variable, but it
- -- doesn't have to be when reading interface files
+type HsContext name = [HsPred name]
+type HsClassAssertion name = (name, [HsType name])
+-- The type is usually a type variable, but it
+-- doesn't have to be when reading interface files
+data HsPred name =
+ HsPClass name [HsType name]
+ | HsPIParam name (HsType name)
data HsType name
= HsForAllTy (Maybe [HsTyVar name]) -- Nothing for implicitly quantified signatures
- (Context name)
+ (HsContext name)
(HsType name)
| MonoTyVar name -- Type variable
| MonoTupleTy [HsType name] -- Element types (length gives arity)
Bool -- boxed?
+ | MonoIParamTy name (HsType name)
+
-- these next two are only used in interfaces
| MonoDictTy name -- Class
[HsType name]
| MonoUsVar name
-mkHsForAllTy [] [] ty = ty
-mkHsForAllTy tvs ctxt ty = HsForAllTy (Just tvs) ctxt ty
+-- Combine adjacent for-alls.
+-- The following awkward situation can happen otherwise:
+-- f :: forall a. ((Num a) => Int)
+-- might generate HsForAll (Just [a]) [] (HsForAll Nothing [Num a] t)
+-- Then a isn't discovered as ambiguous, and we abstract the AbsBinds wrt []
+-- but the export list abstracts f wrt [a]. Disaster.
+--
+-- A valid type must have one for-all at the top of the type, or of the fn arg types
+
+mkHsForAllTy (Just []) [] ty = ty -- Explicit for-all with no tyvars
+mkHsForAllTy mtvs1 [] (HsForAllTy mtvs2 ctxt ty) = mkHsForAllTy (mtvs1 `plus` mtvs2) ctxt ty
+ where
+ mtvs1 `plus` Nothing = mtvs1
+ Nothing `plus` mtvs2 = mtvs2
+ (Just tvs1) `plus` (Just tvs2) = Just (tvs1 ++ tvs2)
+mkHsForAllTy tvs ctxt ty = HsForAllTy tvs ctxt ty
mkHsUsForAllTy uvs ty = foldr (\ uv ty -> MonoUsgForAllTy uv ty)
ty uvs
ppr (UserTyVar name) = ppr name
ppr (IfaceTyVar name kind) = hsep [ppr name, dcolon, ppr kind]
-pprForAll [] = empty
+-- Better to see those for-alls
+-- pprForAll [] = empty
pprForAll tvs = ptext SLIT("forall") <+> interppSP tvs <> ptext SLIT(".")
-pprContext :: (Outputable name) => Context name -> SDoc
-pprContext [] = empty
-pprContext context = parens (hsep (punctuate comma (map pprClassAssertion context))) <+> ptext SLIT("=>")
+pprHsContext :: (Outputable name) => HsContext name -> SDoc
+pprHsContext [] = empty
+pprHsContext context = parens (hsep (punctuate comma (map pprHsPred context))) <+> ptext SLIT("=>")
-pprClassAssertion :: (Outputable name) => ClassAssertion name -> SDoc
-pprClassAssertion (clas, tys)
+pprHsClassAssertion :: (Outputable name) => HsClassAssertion name -> SDoc
+pprHsClassAssertion (clas, tys)
= ppr clas <+> hsep (map pprParendHsType tys)
+
+pprHsPred :: (Outputable name) => HsPred name -> SDoc
+pprHsPred (HsPClass clas tys)
+ = ppr clas <+> hsep (map pprParendHsType tys)
+pprHsPred (HsPIParam n ty)
+ = hsep [{- char '?' <> -} ppr n, text "::", ppr ty]
\end{code}
\begin{code}
ppr_mono_ty ctxt_prec (HsForAllTy maybe_tvs ctxt ty)
= maybeParen (ctxt_prec >= pREC_FUN) $
- sep [pprForAll tvs, pprContext ctxt, pprHsType ty]
+ sep [pp_tvs, pprHsContext ctxt, pprHsType ty]
where
- tvs = case maybe_tvs of
- Just tvs -> tvs
- Nothing -> []
+ pp_tvs = case maybe_tvs of
+ Just tvs -> pprForAll tvs
+ Nothing -> text "{- implicit forall -}"
ppr_mono_ty ctxt_prec (MonoTyVar name)
= ppr name
= maybeParen (ctxt_prec >= pREC_CON)
(hsep [ppr_mono_ty pREC_FUN fun_ty, ppr_mono_ty pREC_CON arg_ty])
+ppr_mono_ty ctxt_prec (MonoIParamTy n ty)
+ = hsep [{- char '?' <> -} ppr n, text "::", ppr_mono_ty pREC_TOP ty]
+
ppr_mono_ty ctxt_prec (MonoDictTy clas tys)
= ppr clas <+> hsep (map (ppr_mono_ty pREC_CON) tys)
wrong}, so be careful!
\begin{code}
-cmpHsTyVar :: (a -> a -> Ordering) -> HsTyVar a -> HsTyVar a -> Ordering
-cmpHsType :: (a -> a -> Ordering) -> HsType a -> HsType a -> Ordering
-cmpHsTypes :: (a -> a -> Ordering) -> [HsType a] -> [HsType a] -> Ordering
-cmpContext :: (a -> a -> Ordering) -> Context a -> Context a -> Ordering
+cmpHsTyVar :: (a -> a -> Ordering) -> HsTyVar a -> HsTyVar a -> Ordering
+cmpHsType :: (a -> a -> Ordering) -> HsType a -> HsType a -> Ordering
+cmpHsTypes :: (a -> a -> Ordering) -> [HsType a] -> [HsType a] -> Ordering
+cmpHsContext :: (a -> a -> Ordering) -> HsContext a -> HsContext a -> Ordering
+cmpHsPred :: (a -> a -> Ordering) -> HsPred a -> HsPred a -> Ordering
cmpHsTyVar cmp (UserTyVar v1) (UserTyVar v2) = v1 `cmp` v2
cmpHsTyVar cmp (IfaceTyVar v1 _) (IfaceTyVar v2 _) = v1 `cmp` v2
cmpHsTyVar cmp (UserTyVar _) other = LT
cmpHsTyVar cmp other1 other2 = GT
-
cmpHsTypes cmp [] [] = EQ
cmpHsTypes cmp [] tys2 = LT
cmpHsTypes cmp tys1 [] = GT
cmpHsType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
= cmpMaybe (cmpList (cmpHsTyVar cmp)) tvs1 tvs2 `thenCmp`
- cmpContext cmp c1 c2 `thenCmp`
+ cmpHsContext cmp c1 c2 `thenCmp`
cmpHsType cmp t1 t2
cmpHsType cmp (MonoTyVar n1) (MonoTyVar n2)
tag (HsForAllTy _ _ _) = ILIT(9)
-------------------
-cmpContext cmp a b
- = cmpList cmp_ctxt a b
- where
- cmp_ctxt (c1, tys1) (c2, tys2)
- = cmp c1 c2 `thenCmp` cmpHsTypes cmp tys1 tys2
+cmpHsContext cmp a b
+ = cmpList (cmpHsPred cmp) a b
+
+cmpHsPred cmp (HsPClass c1 tys1) (HsPClass c2 tys2)
+ = cmp c1 c2 `thenCmp` cmpHsTypes cmp tys1 tys2
+cmpHsPred cmp (HsPIParam n1 ty1) (HsPIParam n2 ty2)
+ = cmp n1 n2 `thenCmp` cmpHsType cmp ty1 ty2
+cmpHsPred cmp (HsPClass _ _) (HsPIParam _ _) = LT
+cmpHsPred cmp _ _ = GT
cmpUsg cmp MonoUsOnce MonoUsOnce = EQ
cmpUsg cmp MonoUsMany MonoUsMany = EQ
projects / ghc-hetmet.git / blobdiff