X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FCoercion.lhs;h=e17d0b007275a8e95fb4a75d8fdb7fc5c9dafdff;hp=1dbd7f3eab1a1a6316a9eabee06c192d12a88d17;hb=b88025eabcd83f65d1d81f09272f5172f06a60e7;hpb=d76c18e05f6366c23144624b696a02fbaa6d26e8 diff --git a/compiler/types/Coercion.lhs b/compiler/types/Coercion.lhs index 1dbd7f3..e17d0b0 100644 --- a/compiler/types/Coercion.lhs +++ b/compiler/types/Coercion.lhs @@ -1,5 +1,8 @@ +% +% (c) The University of Glasgow 2006 +% - Module for type coercions, as in System FC. +Module for type coercions, as in System FC. Coercions are represented as types, and their kinds tell what types the coercion works on. @@ -34,31 +37,18 @@ module Coercion ( #include "HsVersions.h" import TypeRep -import Type ( Type, Kind, PredType, substTyWith, mkAppTy, mkForAllTy, - mkFunTy, splitAppTy_maybe, splitForAllTy_maybe, coreView, - kindView, mkTyConApp, isCoercionKind, isEqPred, mkAppTys, - coreEqType, splitAppTys, isTyVarTy, splitTyConApp_maybe, - tyVarsOfType, mkTyVarTys - ) -import TyCon ( TyCon, tyConArity, mkCoercionTyCon, isClosedNewTyCon, - newTyConRhs, newTyConCo_maybe, - isCoercionTyCon, isCoercionTyCon_maybe ) -import Var ( Var, TyVar, isTyVar, tyVarKind ) -import VarSet ( elemVarSet ) -import Name ( BuiltInSyntax(..), Name, mkWiredInName, tcName ) -import OccName ( mkOccNameFS ) -import PrelNames ( symCoercionTyConKey, - transCoercionTyConKey, leftCoercionTyConKey, - rightCoercionTyConKey, instCoercionTyConKey, - unsafeCoercionTyConKey, gHC_PRIM - ) -import Util ( lengthIs, snocView ) -import Unique ( hasKey ) -import BasicTypes ( Arity ) +import Type +import TyCon +import Var +import Name +import OccName +import PrelNames +import Util +import Unique +import BasicTypes import Outputable - ------------------------------ decomposeCo :: Arity -> Coercion -> [Coercion] -- (decomposeCo 3 c) = [right (left (left c)), right (left c), right c] @@ -101,17 +91,14 @@ splitCoercionKind_maybe co | Just co' <- kindView co = splitCoercionKind_maybe c splitCoercionKind_maybe (PredTy (EqPred ty1 ty2)) = Just (ty1, ty2) splitCoercionKind_maybe other = Nothing -isCoVar :: Var -> Bool -isCoVar tv = isTyVar tv && isCoercionKind (tyVarKind tv) - type Coercion = Type type CoercionKind = Kind -- A CoercionKind is always of form (ty1 :=: ty2) coercionKind :: Coercion -> (Type, Type) -- c :: (t1 :=: t2) -- Then (coercionKind c) = (t1,t2) -coercionKind (TyVarTy a) | isCoVar a = splitCoercionKind (tyVarKind a) - | otherwise = let t = (TyVarTy a) in (t, t) +coercionKind ty@(TyVarTy a) | isCoVar a = splitCoercionKind (tyVarKind a) + | otherwise = (ty, ty) coercionKind (AppTy ty1 ty2) = let (t1, t2) = coercionKind ty1 (s1, s2) = coercionKind ty2 in @@ -119,10 +106,11 @@ coercionKind (AppTy ty1 ty2) coercionKind (TyConApp tc args) | Just (ar, rule) <- isCoercionTyCon_maybe tc -- CoercionTyCons carry their kinding rule, so we use it here - = if length args >= ar - then splitCoercionKind (rule args) - else pprPanic ("arity/arguments mismatch in coercionKind:") - (ppr ar $$ ppr tc <+> ppr args) + = ASSERT( length args >= ar ) -- Always saturated + let (ty1,ty2) = rule (take ar args) -- Apply the rule to the right number of args + (tys1, tys2) = coercionKinds (drop ar args) + in (mkAppTys ty1 tys1, mkAppTys ty2 tys2) + | otherwise = let (lArgs, rArgs) = coercionKinds args in (TyConApp tc lArgs, TyConApp tc rArgs) @@ -287,42 +275,14 @@ mkUnsafeCoercion ty1 ty2 -- See note [Newtype coercions] in TyCon -mkNewTypeCoercion :: Name -> TyCon -> [TyVar] -> Type -> TyCon -mkNewTypeCoercion name tycon tvs rhs_ty - = ASSERT (length tvs == tyConArity tycon) - mkCoercionTyCon name co_con_arity (mkKindingFun rule) +mkNewTypeCoercion :: Name -> TyCon -> ([TyVar], Type) -> TyCon +mkNewTypeCoercion name tycon (tvs, rhs_ty) + = mkCoercionTyCon name co_con_arity rule where - rule args = (TyConApp tycon tys, substTyWith tvs_eta tys rhs_eta, rest) - where - tys = take co_con_arity args - rest = drop co_con_arity args - - -- if the rhs_ty is a type application and it has a tail equal to a tail - -- of the tvs, then we eta-contract the type of the coercion - rhs_args = let (ty, ty_args) = splitAppTys rhs_ty in ty_args - - n_eta_tys = count_eta (reverse rhs_args) (reverse tvs) - - count_eta ((TyVarTy tv):rest_ty) (tv':rest_tv) - | tv == tv' && (not $ any (elemVarSet tv . tyVarsOfType) rest_ty) - -- if the last types are the same, and not free anywhere else - -- then eta contract - = 1 + (count_eta rest_ty rest_tv) - | otherwise -- don't - = 0 - count_eta _ _ = 0 - - - eqVar (TyVarTy tv) tv' = tv == tv' - eqVar _ _ = False + co_con_arity = length tvs - co_con_arity = (tyConArity tycon) - n_eta_tys - - tvs_eta = (reverse (drop n_eta_tys (reverse tvs))) - - rhs_eta - | (ty, ty_args) <- splitAppTys rhs_ty - = mkAppTys ty (reverse (drop n_eta_tys (reverse ty_args))) + rule args = ASSERT( co_con_arity == length args ) + (TyConApp tycon args, substTyWith tvs args rhs_ty) -- Coercion identifying a data/newtype representation type and its family -- instance. It has the form `Co tvs :: F ts :=: R tvs', where `Co' is the @@ -336,17 +296,12 @@ mkDataInstCoercion :: Name -- unique name for the coercion tycon -> TyCon -- representation tycon (`R') -> TyCon -- => coercion tycon (`Co') mkDataInstCoercion name tvs family instTys rep_tycon - = mkCoercionTyCon name coArity (mkKindingFun rule) + = mkCoercionTyCon name coArity rule where coArity = length tvs - - rule args = (substTyWith tvs tys $ -- with sigma = [tys/tvs], + rule args = (substTyWith tvs args $ -- with sigma = [tys/tvs], TyConApp family instTys, -- sigma (F ts) - TyConApp rep_tycon tys, -- :=: R tys - rest) -- surplus arguments - where - tys = take coArity args - rest = drop coArity args + TyConApp rep_tycon args) -- :=: R tys -------------------------------------- -- Coercion Type Constructors... @@ -357,14 +312,6 @@ mkDataInstCoercion name tvs family instTys rep_tycon -- sym d :: p2=q2 -- sym e :: p3=q3 -- then ((sym c) (sym d) (sym e)) :: (p1 p2 p3)=(q1 q2 q3) --- --- (mkKindingFun f) is given the args [c, sym d, sym e] -mkKindingFun :: ([Type] -> (Type, Type, [Type])) -> [Type] -> Kind -mkKindingFun f args = - let (ty1, ty2, rest) = f args in - let (argtys1, argtys2) = unzip (map coercionKind rest) in - mkCoKind (mkAppTys ty1 argtys1) (mkAppTys ty2 argtys2) - symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, instCoercionTyCon :: TyCon -- Each coercion TyCon is built with the special CoercionTyCon record and @@ -372,33 +319,34 @@ symCoercionTyCon, transCoercionTyCon, leftCoercionTyCon, rightCoercionTyCon, ins -- by any TyConApp in which they are applied, however they may also be over -- applied (see example above) and the kinding function must deal with this. symCoercionTyCon = - mkCoercionTyCon symCoercionTyConName 1 (mkKindingFun flipCoercionKindOf) + mkCoercionTyCon symCoercionTyConName 1 flipCoercionKindOf where - flipCoercionKindOf (co:rest) = (ty2, ty1, rest) + flipCoercionKindOf (co:rest) = ASSERT( null rest ) (ty2, ty1) where (ty1, ty2) = coercionKind co transCoercionTyCon = - mkCoercionTyCon transCoercionTyConName 2 (mkKindingFun composeCoercionKindsOf) + mkCoercionTyCon transCoercionTyConName 2 composeCoercionKindsOf where - composeCoercionKindsOf (co1:co2:rest) = + composeCoercionKindsOf (co1:co2:rest) + = ASSERT( null rest ) WARN( not (r1 `coreEqType` a2), text "Strange! Type mismatch in trans coercion, probably a bug") - (a1, r2, rest) + (a1, r2) where (a1, r1) = coercionKind co1 (a2, r2) = coercionKind co2 leftCoercionTyCon = - mkCoercionTyCon leftCoercionTyConName 1 (mkKindingFun leftProjectCoercionKindOf) + mkCoercionTyCon leftCoercionTyConName 1 leftProjectCoercionKindOf where - leftProjectCoercionKindOf (co:rest) = (ty1, ty2, rest) + leftProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2) where (ty1,ty2) = fst (splitCoercionKindOf co) rightCoercionTyCon = - mkCoercionTyCon rightCoercionTyConName 1 (mkKindingFun rightProjectCoercionKindOf) + mkCoercionTyCon rightCoercionTyConName 1 rightProjectCoercionKindOf where - rightProjectCoercionKindOf (co:rest) = (ty1, ty2, rest) + rightProjectCoercionKindOf (co:rest) = ASSERT( null rest ) (ty1, ty2) where (ty1,ty2) = snd (splitCoercionKindOf co) @@ -414,25 +362,26 @@ splitCoercionKindOf co = ((ty_fun1, ty_fun2),(ty_arg1, ty_arg2)) instCoercionTyCon - = mkCoercionTyCon instCoercionTyConName 2 (mkKindingFun instCoercionKind) + = mkCoercionTyCon instCoercionTyConName 2 instCoercionKind where instantiateCo t s = let Just (tv, ty) = splitForAllTy_maybe t in substTyWith [tv] [s] ty - instCoercionKind (co1:ty:rest) = (instantiateCo t1 ty, instantiateCo t2 ty, rest) + instCoercionKind (co1:ty:rest) = ASSERT( null rest ) + (instantiateCo t1 ty, instantiateCo t2 ty) where (t1, t2) = coercionKind co1 unsafeCoercionTyCon - = mkCoercionTyCon unsafeCoercionTyConName 2 (mkKindingFun unsafeCoercionKind) + = mkCoercionTyCon unsafeCoercionTyConName 2 unsafeCoercionKind where - unsafeCoercionKind (ty1:ty2:rest) = (ty1,ty2,rest) + unsafeCoercionKind (ty1:ty2:rest) = ASSERT( null rest ) (ty1,ty2) -------------------------------------- -- ...and their names mkCoConName occ key coCon = mkWiredInName gHC_PRIM (mkOccNameFS tcName occ) - key Nothing (ATyCon coCon) BuiltInSyntax + key (ATyCon coCon) BuiltInSyntax transCoercionTyConName = mkCoConName FSLIT("trans") transCoercionTyConKey transCoercionTyCon symCoercionTyConName = mkCoConName FSLIT("sym") symCoercionTyConKey symCoercionTyCon