tcExpr in_expr@(SectionL arg1 op) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn ->
tcExpr in_expr@(SectionR op arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn ->
tcExpr in_expr@(OpApp arg1 op fix arg2) res_ty
= tcInferRho op `thenM` \ (op', op_ty) ->
- unifyFunTys 2 op_ty {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ unifyInfixTy op in_expr op_ty `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
= tcApp e1 (e2:args) res_ty -- Accumulate the arguments
tcApp fun args res_ty
- = do { (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
+ = do { let n_args = length args
+ ; (fun', fun_tvs, fun_tau) <- tcFun fun -- Type-check the function
-- Extract its argument types
; (expected_arg_tys, actual_res_ty)
- <- addErrCtxt (wrongArgsCtxt "too many" fun args) $ do
- { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau))
- ; unifyFunTys (length args) fun_tau }
-
+ <- do { traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_tau))
+ ; let msg = sep [ptext SLIT("The function") <+> quotes (ppr fun),
+ ptext SLIT("is applied to")
+ <+> speakN n_args <+> ptext SLIT("arguments")]
+ ; unifyFunTys msg n_args fun_tau }
; case res_ty of
Check _ -> do -- Connect to result type first
| otherwise = appCtxt fun args
in
returnM (env2, message)
+
+----------------
+unifyInfixTy :: LHsExpr Name -> HsExpr Name -> TcType
+ -> TcM ([TcType], TcType)
+-- This wrapper just prepares the error message for unifyFunTys
+unifyInfixTy op expr op_ty
+ = unifyFunTys msg 2 op_ty
+ where
+ msg = sep [herald <+> quotes (ppr expr),
+ ptext SLIT("requires") <+> quotes (ppr op)
+ <+> ptext SLIT("to take two arguments")]
+ herald = case expr of
+ OpApp _ _ _ _ -> ptext SLIT("The infix expression")
+ other -> ptext SLIT("The operator section")
\end{code}
tyConFieldType :: TyCon -> FieldLabel -> Type
tyConFieldType tycon field_lbl
= case [ty | (f,ty,_) <- tyConFields tycon, f == field_lbl] of
+ [] -> panic "tyConFieldType"
(ty:other) -> ASSERT( null other) ty
-- This lookup and assertion will surely succeed, because
-- we check that the fields are indeed record selectors
= tcCheckRho expr ty `thenM` \ expr' ->
tcCheckRhos exprs tys `thenM` \ exprs' ->
returnM (expr':exprs')
+tcCheckRhos exprs tys = pprPanic "tcCheckRhos" (ppr exprs $$ ppr tys)
\end{code}
#include "HsVersions.h"
-import HsSyn ( HsExpr(..) , MatchGroup(..), hsLMatchPats )
+import HsSyn ( HsExpr(..) , MatchGroup(..), HsMatchContext(..),
+ hsLMatchPats, pprMatches, pprMatchContext )
import TcHsSyn ( mkHsLet, mkHsDictLam,
ExprCoFn, idCoercion, isIdCoercion, mkCoercion, (<.>), (<$>) )
import TypeRep ( Type(..), PredType(..), TyNote(..) )
import TcType ( TcKind, TcType, TcSigmaType, TcRhoType, TcTyVar, TcTauType,
TcTyVarSet, TcThetaType, Expected(..), TcTyVarDetails(..),
SkolemInfo( GenSkol ), MetaDetails(..),
- pprTcTyVar, isTauTy, isSigmaTy, mkFunTys, mkTyConApp,
+ pprTcTyVar, isTauTy, isSigmaTy, mkFunTy, mkFunTys, mkTyConApp,
tcSplitAppTy_maybe, tcSplitTyConApp_maybe,
tyVarsOfType, mkPhiTy, mkTyVarTy, mkPredTy,
typeKind, tcSplitFunTy_maybe, mkForAllTys, mkAppTy,
import Var ( Var, varName, tyVarKind )
import VarSet ( emptyVarSet, unitVarSet, unionVarSet, elemVarSet, varSetElems )
import VarEnv
-import Name ( isSystemName, mkSysTvName )
+import Name ( Name, isSystemName, mkSysTvName )
import ErrUtils ( Message )
import SrcLoc ( noLoc )
import BasicTypes ( Arity )
type variables, so we should create new ordinary type variables
\begin{code}
-subFunTys :: MatchGroup name
+subFunTys :: HsMatchContext Name
+ -> MatchGroup Name
-> Expected TcRhoType -- Fail if ty isn't a function type
-> ([Expected TcRhoType] -> Expected TcRhoType -> TcM a)
-> TcM a
-subFunTys (MatchGroup (match:null_matches) _) (Infer hole) thing_inside
+subFunTys ctxt (MatchGroup (match:null_matches) _) (Infer hole) thing_inside
= -- This is the interesting case
ASSERT( null null_matches )
do { pat_holes <- mapM (\ _ -> newHole) (hsLMatchPats match)
-- And return the answer
; return res }
-subFunTys (MatchGroup (match:matches) _) (Check ty) thing_inside
- = ASSERT( all ((== length (hsLMatchPats match)) . length . hsLMatchPats) matches )
+subFunTys ctxt group@(MatchGroup (match:matches) _) (Check ty) thing_inside
+ = ASSERT( all ((== n_pats) . length . hsLMatchPats) matches )
-- Assertion just checks that all the matches have the same number of pats
- do { (pat_tys, res_ty) <- unifyFunTys (length (hsLMatchPats match)) ty
+ do { (pat_tys, res_ty) <- unifyFunTys msg n_pats ty
; thing_inside (map Check pat_tys) (Check res_ty) }
-
-unifyFunTys :: Arity -> TcRhoType -> TcM ([TcSigmaType], TcRhoType)
+ where
+ n_pats = length (hsLMatchPats match)
+ msg = case ctxt of
+ FunRhs fun -> ptext SLIT("The equation(s) for") <+> quotes (ppr fun)
+ <+> ptext SLIT("have") <+> speakN n_pats <+> ptext SLIT("arguments")
+ LambdaExpr -> sep [ ptext SLIT("The lambda expression")
+ <+> quotes (pprSetDepth 1 $ pprMatches ctxt group),
+ -- The pprSetDepth makes the abstraction print briefly
+ ptext SLIT("has") <+> speakN n_pats <+> ptext SLIT("arguments")]
+ other -> pprPanic "subFunTys" (pprMatchContext ctxt)
+
+
+unifyFunTys :: SDoc -> Arity -> TcRhoType -> TcM ([TcSigmaType], TcRhoType)
-- Fail if ty isn't a function type, otherwise return arg and result types
-- The result types are guaranteed wobbly if the argument is wobbly
--
--
-- (b) GADTs: if the argument is not wobbly we do not want the result to be
-unifyFunTys arity ty = unify_fun_ty True arity ty
+{-
+ Error messages from unifyFunTys
+ The first line is passed in as error_herald
+
+ The abstraction `\Just 1 -> ...' has two arguments
+ but its type `Maybe a -> a' has only one
+
+ The equation(s) for `f' have two arguments
+ but its type `Maybe a -> a' has only one
+
+ The section `(f 3)' requires 'f' to take two arguments
+ but its type `Int -> Int' has only one
+
+ The function 'f' is applied to two arguments
+ but its type `Int -> Int' has only one
+-}
+
+unifyFunTys error_herald arity ty
+ -- error_herald is the whole first line of the error message above
+ = do { (ok, args, res) <- unify_fun_ty True arity ty
+ ; if ok then return (args, res)
+ else failWithTc (mk_msg (length args)) }
+ where
+ mk_msg n_actual
+ = error_herald <> comma $$
+ sep [ptext SLIT("but its type") <+> quotes (pprType ty),
+ ptext SLIT("has only") <+> speakN n_actual]
+
+unify_fun_ty :: Bool -> Arity -> TcRhoType
+ -> TcM (Bool, -- Arity satisfied?
+ [TcSigmaType], -- Arg types found; length <= arity
+ TcRhoType) -- Result type
unify_fun_ty use_refinement arity ty
| arity == 0
= do { res_ty <- wobblify use_refinement ty
- ; return ([], ty) }
+ ; return (True, [], ty) }
unify_fun_ty use_refinement arity (NoteTy _ ty)
= unify_fun_ty use_refinement arity ty
= do { details <- condLookupTcTyVar use_refinement tv
; case details of
IndirectTv use' ty' -> unify_fun_ty use' arity ty'
- other -> unify_fun_help arity ty
+ DoneTv (MetaTv ref) -> ASSERT( liftedTypeKind `isSubKind` tyVarKind tv )
+ -- The argument to unifyFunTys is always a type
+ -- Occurs check can't happen, of course
+ do { args <- mappM newTyFlexiVarTy (replicate arity argTypeKind)
+ ; res <- newTyFlexiVarTy openTypeKind
+ ; writeMutVar ref (Indirect (mkFunTys args res))
+ ; return (True, args, res) }
+ DoneTv skol -> return (False, [], ty)
}
unify_fun_ty use_refinement arity ty
- = case tcSplitFunTy_maybe ty of
- Just (arg,res) -> do { arg' <- wobblify use_refinement arg
- ; (args', res') <- unify_fun_ty use_refinement (arity-1) res
- ; return (arg':args', res') }
-
- Nothing -> unify_fun_help arity ty
- -- Usually an error, but ty could be (a Int Bool), which can match
-
-unify_fun_help :: Arity -> TcRhoType -> TcM ([TcSigmaType], TcRhoType)
-unify_fun_help arity ty
- = do { args <- mappM newTyFlexiVarTy (replicate arity argTypeKind)
- ; res <- newTyFlexiVarTy openTypeKind
- ; unifyTauTy ty (mkFunTys args res)
- ; return (args, res) }
+ | Just (arg,res) <- tcSplitFunTy_maybe ty
+ = do { arg' <- wobblify use_refinement arg
+ ; (ok, args', res') <- unify_fun_ty use_refinement (arity-1) res
+ ; return (ok, arg':args', res') }
+
+unify_fun_ty use_refinement arity ty
+-- Common cases are all done by now
+-- At this point we usually have an error, but ty could
+-- be (a Int Bool), or (a Bool), which can match
+-- So just use the unifier. But catch any error so we just
+-- return the success/fail boolean
+ = do { arg <- newTyFlexiVarTy argTypeKind
+ ; res <- newTyFlexiVarTy openTypeKind
+ ; let fun_ty = mkFunTy arg res
+ ; (_, mb_unit) <- tryTc (uTys True ty ty True fun_ty fun_ty)
+ ; case mb_unit of {
+ Nothing -> return (False, [], ty) ;
+ Just _ ->
+ do { (ok, args', res') <- unify_fun_ty use_refinement (arity-1) res
+ ; return (ok, arg:args', res')
+ } } }
\end{code}
\begin{code}
-- I'm not quite sure what to do about this!
tc_sub exp_sty exp_ty@(FunTy exp_arg exp_res) _ act_ty
- = do { ([act_arg], act_res) <- unifyFunTys 1 act_ty
+ = do { (act_arg, act_res) <- unify_fun act_ty
; tcSub_fun exp_arg exp_res act_arg act_res }
tc_sub _ exp_ty act_sty act_ty@(FunTy act_arg act_res)
- = do { ([exp_arg], exp_res) <- unifyFunTys 1 exp_ty
+ = do { (exp_arg, exp_res) <- unify_fun exp_ty
; tcSub_fun exp_arg exp_res act_arg act_res }
-----------------------------------
tc_sub exp_sty expected_ty act_sty actual_ty
= uTys True exp_sty expected_ty True act_sty actual_ty `thenM_`
returnM idCoercion
+
+-----------------------------------
+-- A helper to make a function type match
+-- The error message isn't very good, but that's a problem with
+-- all of this subsumption code
+unify_fun ty
+ = do { (ok, args, res) <- unify_fun_ty True 1 ty
+ ; if ok then return (head args, res)
+ else failWithTc (ptext SLIT("Expecting a function type, but found") <+> quotes (ppr ty))}
\end{code}
\begin{code}
projects / ghc-hetmet.git / commitdiff