\section[TcExpr]{Typecheck an expression}
\begin{code}
-module TcExpr ( tcExpr, tcExpr_id, tcMonoExpr ) where
+module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where
#include "HsVersions.h"
#ifdef GHCI /* Only if bootstrapped */
import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
-import HsSyn ( HsReify(..), ReifyFlavour(..) )
-import TcType ( isTauTy )
-import TcEnv ( bracketOK, tcMetaTy, tcLookupGlobal,
- wellStaged, metaLevel )
-import TcSimplify ( tcSimplifyBracket )
+import Id ( Id )
import Name ( isExternalName )
+import TcType ( isTauTy )
+import TcEnv ( checkWellStaged )
+import HsSyn ( nlHsApp )
import qualified DsMeta
#endif
-import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..), recBindFields )
-import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, mkHsLet )
+import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
+ HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar )
+import TcHsSyn ( hsLitType, (<$>) )
import TcRnMonad
-import TcUnify ( tcSubExp, tcGen, (<$>),
- unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy,
- unifyTupleTy )
+import TcUnify ( Expected(..), tcInfer, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
+ unifyFunTys, zapToListTy, zapToTyConApp )
import BasicTypes ( isMarkedStrict )
-import Inst ( InstOrigin(..),
- newOverloadedLit, newMethodFromName, newIPDict,
- newDicts, newMethodWithGivenTy,
- instToId, tcInstCall, tcInstDataCon
- )
+import Inst ( newOverloadedLit, newMethodFromName, newIPDict,
+ newDicts, newMethodWithGivenTy, tcInstStupidTheta, tcInstCall )
import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupClass, tcLookupGlobal_maybe, tcLookupIdLvl,
- tcLookupTyCon, tcLookupDataCon, tcLookupId
+import TcEnv ( tcLookup, tcLookupId, checkProcLevel,
+ tcLookupDataCon, tcLookupGlobalId
)
-import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts )
-import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
-import TcPat ( badFieldCon )
-import TcMType ( tcInstTyVars, tcInstType, newHoleTyVarTy, zapToType,
- newTyVarTy, newTyVarTys, zonkTcType, readHoleResult )
-import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
+import TcArrows ( tcProc )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) )
+import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
+import TcPat ( badFieldCon, refineTyVars )
+import TcMType ( tcInstTyVars, tcInstType, newTyFlexiVarTy, zonkTcType )
+import TcType ( Type, TcTyVar, TcType, TcSigmaType, TcRhoType,
tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
- isSigmaTy, mkFunTy, mkFunTys,
- mkTyConApp, mkClassPred, tcFunArgTy,
- tyVarsOfTypes, isLinearPred,
- liftedTypeKind, openTypeKind,
- tcSplitSigmaTy, tcTyConAppTyCon,
- tidyOpenType
+ isSigmaTy, mkFunTy, mkTyConApp, tyVarsOfTypes, isLinearPred,
+ tcSplitSigmaTy, tidyOpenType
)
-import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector, isDataConWrapId_maybe )
-import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks )
+import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
+
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId )
import Name ( Name )
-import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
-import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import TyCon ( TyCon, FieldLabel, tyConTyVars, tyConStupidTheta,
+ tyConDataCons, tyConFields )
+import Type ( zipTopTvSubst, substTheta, substTy )
+import Var ( tyVarKind )
import VarSet ( emptyVarSet, elemVarSet )
-import TysWiredIn ( boolTy )
-import PrelNames ( cCallableClassName, cReturnableClassName,
- enumFromName, enumFromThenName,
+import TysWiredIn ( boolTy, parrTyCon, tupleTyCon )
+import PrelNames ( enumFromName, enumFromThenName,
enumFromToName, enumFromThenToName,
- enumFromToPName, enumFromThenToPName,
- ioTyConName
+ enumFromToPName, enumFromThenToPName
)
import ListSetOps ( minusList )
import CmdLineOpts
import HscTypes ( TyThing(..) )
-
+import SrcLoc ( Located(..), unLoc, getLoc )
import Util
import Outputable
import FastString
+
+#ifdef DEBUG
+import TyCon ( isAlgTyCon )
+#endif
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr :: RenamedHsExpr -- Expession to type check
- -> TcSigmaType -- Expected type (could be a polytpye)
- -> TcM TcExpr -- Generalised expr with expected type
+-- tcCheckSigma does type *checking*; it's passed the expected type of the result
+tcCheckSigma :: LHsExpr Name -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM (LHsExpr TcId) -- Generalised expr with expected type
-tcExpr expr expected_ty
+tcCheckSigma expr expected_ty
= traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
tc_expr' expr expected_ty
-tc_expr' expr expected_ty
- | not (isSigmaTy expected_ty) -- Monomorphic case
- = tcMonoExpr expr expected_ty
-
- | otherwise
- = tcGen expected_ty emptyVarSet (
- tcMonoExpr expr
+tc_expr' expr sigma_ty
+ | isSigmaTy sigma_ty
+ = tcGen sigma_ty emptyVarSet (
+ \ rho_ty -> tcCheckRho expr rho_ty
) `thenM` \ (gen_fn, expr') ->
- returnM (gen_fn <$> expr')
+ returnM (L (getLoc expr') (gen_fn <$> unLoc expr'))
+
+tc_expr' expr rho_ty -- Monomorphic case
+ = tcCheckRho expr rho_ty
+\end{code}
+
+Typecheck expression which in most cases will be an Id.
+The expression can return a higher-ranked type, such as
+ (forall a. a->a) -> Int
+so we must create a hole to pass in as the expected tyvar.
+
+\begin{code}
+tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
+tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty)
+
+tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType)
+tcInferRho (L loc (HsVar name)) = setSrcSpan loc $ do
+ { (e,_,ty) <- tcId name; return (L loc e, ty)}
+tcInferRho expr = tcInfer (tcMonoExpr expr)
\end{code}
+
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{The TAUT rules for variables}TcExpr
%* *
%************************************************************************
\begin{code}
-tcMonoExpr :: RenamedHsExpr -- Expession to type check
- -> TcRhoType -- Expected type (could be a type variable)
+tcMonoExpr :: LHsExpr Name -- Expession to type check
+ -> Expected TcRhoType -- Expected type (could be a type variable)
-- Definitely no foralls at the top
-- Can be a 'hole'.
- -> TcM TcExpr
+ -> TcM (LHsExpr TcId)
-tcMonoExpr (HsVar name) res_ty
- = tcId name `thenM` \ (expr', id_ty) ->
- tcSubExp res_ty id_ty `thenM` \ co_fn ->
- returnM (co_fn <$> expr')
+tcMonoExpr (L loc expr) res_ty
+ = setSrcSpan loc (do { expr' <- tc_expr expr res_ty
+ ; return (L loc expr') })
-tcMonoExpr (HsIPVar ip) res_ty
+tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
+tc_expr (HsVar name) res_ty
+ = do { (expr', _, id_ty) <- tcId name
+ ; co_fn <- tcSubExp res_ty id_ty
+ ; returnM (co_fn <$> expr') }
+
+tc_expr (HsIPVar ip) res_ty
= -- Implicit parameters must have a *tau-type* not a
-- type scheme. We enforce this by creating a fresh
-- type variable as its type. (Because res_ty may not
-- be a tau-type.)
- newTyVarTy openTypeKind `thenM` \ ip_ty ->
- newIPDict (IPOcc ip) ip ip_ty `thenM` \ (ip', inst) ->
+ newTyFlexiVarTy argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
+ newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
extendLIE inst `thenM_`
tcSubExp res_ty ip_ty `thenM` \ co_fn ->
returnM (co_fn <$> HsIPVar ip')
%************************************************************************
\begin{code}
-tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = addErrCtxt (exprSigCtxt in_expr) $
- tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
- tcExpr expr sig_tc_ty `thenM` \ expr' ->
-
- -- Must instantiate the outer for-alls of sig_tc_ty
- -- else we risk instantiating a ? res_ty to a forall-type
- -- which breaks the invariant that tcMonoExpr only returns phi-types
- tcInstCall SignatureOrigin sig_tc_ty `thenM` \ (inst_fn, inst_sig_ty) ->
- tcSubExp res_ty inst_sig_ty `thenM` \ co_fn ->
+tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = addErrCtxt (exprCtxt in_expr) $
+ tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
+ tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') ->
+ returnM (co_fn <$> ExprWithTySigOut expr' poly_ty)
- returnM (co_fn <$> inst_fn expr')
-
-tcMonoExpr (HsType ty) res_ty
+tc_expr (HsType ty) res_ty
= failWithTc (text "Can't handle type argument:" <+> ppr ty)
-- This is the syntax for type applications that I was planning
-- but there are difficulties (e.g. what order for type args)
%************************************************************************
\begin{code}
-tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty
-tcMonoExpr (HsOverLit lit) res_ty = newOverloadedLit (LiteralOrigin lit) lit res_ty
-tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
- returnM (HsPar expr')
-tcMonoExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
- returnM (HsSCC lbl expr')
-
-
-tcMonoExpr (NegApp expr neg_name) res_ty
- = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
+tc_expr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsPar expr')
+tc_expr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsSCC lbl expr')
+tc_expr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
+ returnM (HsCoreAnn lbl expr')
+
+tc_expr (HsLit lit) res_ty = tcLit lit res_ty
+
+tc_expr (HsOverLit lit) res_ty
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ -- Overloaded literals must have liftedTypeKind, because
+ -- we're instantiating an overloaded function here,
+ -- whereas res_ty might be openTypeKind. This was a bug in 6.2.2
+ newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr ->
+ returnM (unLoc lit_expr) -- ToDo: nasty unLoc
+
+tc_expr (NegApp expr neg_name) res_ty
+ = tc_expr (HsApp (nlHsVar neg_name) expr) res_ty
-- ToDo: use tcSyntaxName
-tcMonoExpr (HsLam match) res_ty
+tc_expr (HsLam match) res_ty
= tcMatchLambda match res_ty `thenM` \ match' ->
returnM (HsLam match')
-tcMonoExpr (HsApp e1 e2) res_ty
+tc_expr (HsApp e1 e2) res_ty
= tcApp e1 [e2] res_ty
\end{code}
-- or just
-- op e
-tcMonoExpr in_expr@(SectionL arg1 op) res_ty
- = tcExpr_id op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+tc_expr 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) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn ->
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcMonoExpr in_expr@(SectionR op arg2) res_ty
- = tcExpr_id op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+tc_expr 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) ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn ->
-- equivalent to (op e1) e2:
-tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty
- = tcExpr_id op `thenM` \ (op', op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+tc_expr 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) ->
tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
addErrCtxt (exprCtxt in_expr) $
\end{code}
\begin{code}
-tcMonoExpr (HsLet binds expr) res_ty
+tc_expr (HsLet binds (L loc expr)) res_ty
= tcBindsAndThen
- HsLet
+ glue
binds -- Bindings to check
- (tcMonoExpr expr res_ty)
-
-tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
- = addSrcLoc src_loc $
- addErrCtxt (caseCtxt in_expr) $
+ (setSrcSpan loc $ tc_expr expr res_ty)
+ where
+ glue bind expr = HsLet [bind] (L loc expr)
- -- Typecheck the case alternatives first.
+tc_expr in_expr@(HsCase scrut matches) exp_ty
+ = -- We used to typecheck the case alternatives first.
-- The case patterns tend to give good type info to use
-- when typechecking the scrutinee. For example
-- case (map f) of
-- (x:xs) -> ...
-- will report that map is applied to too few arguments
--
- -- Not only that, but it's better to check the matches on their
- -- own, so that we get the expected results for scoped type variables.
- -- f x = case x of
- -- (p::a, q::b) -> (q,p)
- -- The above should work: the match (p,q) -> (q,p) is polymorphic as
- -- claimed by the pattern signatures. But if we typechecked the
- -- match with x in scope and x's type as the expected type, we'd be hosed.
-
- tcMatchesCase matches res_ty `thenM` \ (scrut_ty, matches') ->
-
- addErrCtxt (caseScrutCtxt scrut) (
- tcMonoExpr scrut scrut_ty
- ) `thenM` \ scrut' ->
-
- returnM (HsCase scrut' matches' src_loc)
-
-tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
- = addSrcLoc src_loc $
- addErrCtxt (predCtxt pred) (
- tcMonoExpr pred boolTy ) `thenM` \ pred' ->
-
- zapToType res_ty `thenM` \ res_ty' ->
+ -- But now, in the GADT world, we need to typecheck the scrutinee
+ -- first, to get type info that may be refined in the case alternatives
+ addErrCtxt (caseScrutCtxt scrut)
+ (tcInferRho scrut) `thenM` \ (scrut', scrut_ty) ->
+
+ addErrCtxt (caseCtxt in_expr) $
+ tcMatchesCase match_ctxt scrut_ty matches exp_ty `thenM` \ matches' ->
+ returnM (HsCase scrut' matches')
+ where
+ match_ctxt = MC { mc_what = CaseAlt,
+ mc_body = tcMonoExpr }
+
+tc_expr (HsIf pred b1 b2) res_ty
+ = addErrCtxt (predCtxt pred) (
+ tcCheckRho pred boolTy ) `thenM` \ pred' ->
+
+ zapExpectedType res_ty openTypeKind `thenM` \ res_ty' ->
-- C.f. the call to zapToType in TcMatches.tcMatches
- tcMonoExpr b1 res_ty' `thenM` \ b1' ->
- tcMonoExpr b2 res_ty' `thenM` \ b2' ->
- returnM (HsIf pred' b1' b2' src_loc)
+ tcCheckRho b1 res_ty' `thenM` \ b1' ->
+ tcCheckRho b2 res_ty' `thenM` \ b2' ->
+ returnM (HsIf pred' b1' b2')
-tcMonoExpr (HsDo do_or_lc stmts method_names _ src_loc) res_ty
- = addSrcLoc src_loc $
- tcDoStmts do_or_lc stmts method_names res_ty `thenM` \ (binds, stmts', methods') ->
- returnM (mkHsLet binds (HsDo do_or_lc stmts' methods' res_ty src_loc))
+tc_expr (HsDo do_or_lc stmts method_names _) res_ty
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ -- All comprehensions yield a monotype of kind *
+ tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') ->
+ returnM (HsDo do_or_lc stmts' methods' res_ty')
-tcMonoExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
- = unifyListTy res_ty `thenM` \ elt_ty ->
+tc_expr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
+ = zapToListTy res_ty `thenM` \ elt_ty ->
mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
returnM (ExplicitList elt_ty exprs')
where
tc_elt elt_ty expr
= addErrCtxt (listCtxt expr) $
- tcMonoExpr expr elt_ty
+ tcCheckRho expr elt_ty
-tcMonoExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
- = unifyPArrTy res_ty `thenM` \ elt_ty ->
- mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
- returnM (ExplicitPArr elt_ty exprs')
+tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+ = do { [elt_ty] <- zapToTyConApp parrTyCon res_ty
+ ; exprs' <- mappM (tc_elt elt_ty) exprs
+ ; return (ExplicitPArr elt_ty exprs') }
where
tc_elt elt_ty expr
- = addErrCtxt (parrCtxt expr) $
- tcMonoExpr expr elt_ty
+ = addErrCtxt (parrCtxt expr) (tcCheckRho expr elt_ty)
-tcMonoExpr (ExplicitTuple exprs boxity) res_ty
- = unifyTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
- tcMonoExprs exprs arg_tys `thenM` \ exprs' ->
- returnM (ExplicitTuple exprs' boxity)
-\end{code}
+tc_expr (ExplicitTuple exprs boxity) res_ty
+ = do { arg_tys <- zapToTyConApp (tupleTyCon boxity (length exprs)) res_ty
+ ; exprs' <- tcCheckRhos exprs arg_tys
+ ; return (ExplicitTuple exprs' boxity) }
+tc_expr (HsProc pat cmd) res_ty
+ = tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
+ returnM (HsProc pat' cmd')
-%************************************************************************
-%* *
- Foreign calls
-%* *
-%************************************************************************
-
-The interesting thing about @ccall@ is that it is just a template
-which we instantiate by filling in details about the types of its
-argument and result (ie minimal typechecking is performed). So, the
-basic story is that we allocate a load of type variables (to hold the
-arg/result types); unify them with the args/result; and store them for
-later use.
-
-\begin{code}
-tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty
-
- = getDOpts `thenM` \ dflags ->
+tc_expr e@(HsArrApp _ _ _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
- checkTc (not (is_casm && dopt_HscLang dflags /= HscC))
- (vcat [text "_casm_ is only supported when compiling via C (-fvia-C).",
- text "Either compile with -fvia-C, or, better, rewrite your code",
- text "to use the foreign function interface. _casm_s are deprecated",
- text "and support for them may one day disappear."])
- `thenM_`
-
- -- Get the callable and returnable classes.
- tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
- tcLookupClass cReturnableClassName `thenM` \ cReturnableClass ->
- tcLookupTyCon ioTyConName `thenM` \ ioTyCon ->
- let
- new_arg_dict (arg, arg_ty)
- = newDicts (CCallOrigin (unpackFS lbl) (Just arg))
- [mkClassPred cCallableClass [arg_ty]] `thenM` \ arg_dicts ->
- returnM arg_dicts -- Actually a singleton bag
-
- result_origin = CCallOrigin (unpackFS lbl) Nothing {- Not an arg -}
- in
-
- -- Arguments
- let tv_idxs | null args = []
- | otherwise = [1..length args]
- in
- newTyVarTys (length tv_idxs) openTypeKind `thenM` \ arg_tys ->
- tcMonoExprs args arg_tys `thenM` \ args' ->
-
- -- The argument types can be unlifted or lifted; the result
- -- type must, however, be lifted since it's an argument to the IO
- -- type constructor.
- newTyVarTy liftedTypeKind `thenM` \ result_ty ->
- let
- io_result_ty = mkTyConApp ioTyCon [result_ty]
- in
- unifyTauTy res_ty io_result_ty `thenM_`
-
- -- Construct the extra insts, which encode the
- -- constraints on the argument and result types.
- mappM new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenM` \ ccarg_dicts_s ->
- newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenM` \ ccres_dict ->
- extendLIEs (ccres_dict ++ concat ccarg_dicts_s) `thenM_`
- returnM (HsCCall lbl args' may_gc is_casm io_result_ty)
+tc_expr e@(HsArrForm _ _ _) _
+ = failWithTc (vcat [ptext SLIT("The arrow command"), nest 2 (ppr e),
+ ptext SLIT("was found where an expression was expected")])
\end{code}
-
%************************************************************************
%* *
Record construction and update
%************************************************************************
\begin{code}
-tcMonoExpr expr@(RecordCon con_name rbinds) res_ty
+tc_expr expr@(RecordCon con@(L loc con_name) rbinds) res_ty
= addErrCtxt (recordConCtxt expr) $
- tcId con_name `thenM` \ (con_expr, con_tau) ->
+ addLocM tcId con `thenM` \ (con_expr, _, con_tau) ->
let
(_, record_ty) = tcSplitFunTys con_tau
(tycon, ty_args) = tcSplitTyConApp record_ty
in
ASSERT( isAlgTyCon tycon )
- unifyTauTy res_ty record_ty `thenM_`
+ zapExpectedTo res_ty record_ty `thenM_`
-- Check that the record bindings match the constructor
-- con_name is syntactically constrained to be a data constructor
- tcLookupDataCon con_name `thenM` \ data_con ->
+ tcLookupDataCon con_name `thenM` \ data_con ->
let
bad_fields = badFields rbinds data_con
in
-- Check for missing fields
checkMissingFields data_con rbinds `thenM_`
- returnM (RecordConOut data_con con_expr rbinds')
+ returnM (RecordConOut data_con (L loc con_expr) rbinds')
-- The main complication with RecordUpd is that we need to explicitly
-- handle the *non-updated* fields. Consider:
--
-- All this is done in STEP 4 below.
-tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty
+tc_expr expr@(RecordUpd record_expr rbinds) res_ty
= addErrCtxt (recordUpdCtxt expr) $
-- STEP 0
-- Check that the field names are really field names
ASSERT( notNull rbinds )
let
- field_names = recBindFields rbinds
+ field_names = map fst rbinds
in
- mappM tcLookupGlobal_maybe field_names `thenM` \ maybe_sel_ids ->
+ mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids ->
+ -- The renamer has already checked that they
+ -- are all in scope
let
- bad_guys = [ addErrTc (notSelector field_name)
- | (field_name, maybe_sel_id) <- field_names `zip` maybe_sel_ids,
- case maybe_sel_id of
- Just (AnId sel_id) -> not (isRecordSelector sel_id)
- other -> True
+ bad_guys = [ setSrcSpan loc $ addErrTc (notSelector field_name)
+ | (L loc field_name, sel_id) <- field_names `zip` sel_ids,
+ not (isRecordSelector sel_id) -- Excludes class ops
]
in
checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_`
-- Figure out the tycon and data cons from the first field name
let
-- It's OK to use the non-tc splitters here (for a selector)
- (Just (AnId sel_id) : _) = maybe_sel_ids
-
- (_, _, tau) = tcSplitSigmaTy (idType sel_id) -- Selectors can be overloaded
- -- when the data type has a context
- data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector
- tycon = tcTyConAppTyCon data_ty
- data_cons = tyConDataCons tycon
+ sel_id : _ = sel_ids
+ (tycon, _) = recordSelectorFieldLabel sel_id -- We've failed already if
+ data_cons = tyConDataCons tycon -- it's not a field label
tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
+ tcInstTyVars tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
-- STEP 2
-- Check that at least one constructor has all the named fields
-- i.e. has an empty set of bad fields returned by badFields
checkTc (any (null . badFields rbinds) data_cons)
- (badFieldsUpd rbinds) `thenM_`
+ (badFieldsUpd rbinds) `thenM_`
-- STEP 3
-- Typecheck the update bindings.
let
result_record_ty = mkTyConApp tycon result_inst_tys
in
- unifyTauTy res_ty result_record_ty `thenM_`
+ zapExpectedTo res_ty result_record_ty `thenM_`
tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' ->
-- STEP 4
-- WARNING: this code assumes that all data_cons in a common tycon
-- have FieldLabels abstracted over the same tyvars.
let
- upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds')
+ upd_field_lbls = recBindFields rbinds
con_field_lbls_s = map dataConFieldLabels data_cons
-- A constructor is only relevant to this process if
is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls
non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
- common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
+ common_tyvars = tyVarsOfTypes [ty | (fld,ty,_) <- tyConFields tycon,
+ fld `elem` non_upd_field_lbls]
+ is_common_tv tv = tv `elemVarSet` common_tyvars
- mk_inst_ty (tyvar, result_inst_ty)
- | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
- | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+ mk_inst_ty tv result_inst_ty
+ | is_common_tv tv = returnM result_inst_ty -- Same as result type
+ | otherwise = newTyFlexiVarTy (tyVarKind tv) -- Fresh type, of correct kind
in
- mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys ->
+ zipWithM mk_inst_ty tycon_tyvars result_inst_tys `thenM` \ inst_tys ->
-- STEP 5
-- Typecheck the expression to be updated
let
record_ty = mkTyConApp tycon inst_tys
in
- tcMonoExpr record_expr record_ty `thenM` \ record_expr' ->
+ tcCheckRho record_expr record_ty `thenM` \ record_expr' ->
-- STEP 6
-- Figure out the LIE we need. We have to generate some
-- What dictionaries do we need?
-- We just take the context of the type constructor
let
- theta' = substTheta inst_env (tyConTheta tycon)
+ theta' = substTheta inst_env (tyConStupidTheta tycon)
in
newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
extendLIEs dicts `thenM_`
%************************************************************************
\begin{code}
-tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
- = unifyListTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr elt_ty `thenM` \ expr' ->
+tc_expr (ArithSeqIn seq@(From expr)) res_ty
+ = zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr elt_ty `thenM` \ expr' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromName `thenM` \ enum_from ->
- returnM (ArithSeqOut (HsVar enum_from) (From expr'))
+ returnM (ArithSeqOut (nlHsVar enum_from) (From expr'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+tc_expr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
= addErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
- tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromThenName `thenM` \ enum_from_then ->
- returnM (ArithSeqOut (HsVar enum_from_then) (FromThen expr1' expr2'))
+ returnM (ArithSeqOut (nlHsVar enum_from_then) (FromThen expr1' expr2'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+tc_expr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
= addErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
- tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromToName `thenM` \ enum_from_to ->
- returnM (ArithSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (ArithSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+tc_expr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
= addErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
- tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
- tcMonoExpr expr3 elt_ty `thenM` \ expr3' ->
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
newMethodFromName (ArithSeqOrigin seq)
elt_ty enumFromThenToName `thenM` \ eft ->
- returnM (ArithSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (ArithSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- unifyPArrTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
- tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromToPName `thenM` \ enum_from_to ->
- returnM (PArrSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
+ returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
= addErrCtxt (parrSeqCtxt in_expr) $
- unifyPArrTy res_ty `thenM` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
- tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
- tcMonoExpr expr3 elt_ty `thenM` \ expr3' ->
+ zapToTyConApp parrTyCon res_ty `thenM` \ [elt_ty] ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
newMethodFromName (PArrSeqOrigin seq)
elt_ty enumFromThenToPName `thenM` \ eft ->
- returnM (PArrSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+ returnM (PArrSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
-tcMonoExpr (PArrSeqIn _) _
+tc_expr (PArrSeqIn _) _
= panic "TcExpr.tcMonoExpr: Infinite parallel array!"
-- the parser shouldn't have generated it and the renamer shouldn't have
-- let it through
\begin{code}
#ifdef GHCI /* Only if bootstrapped */
-- Rename excludes these cases otherwise
-
-tcMonoExpr (HsSplice n expr loc) res_ty = addSrcLoc loc (tcSpliceExpr n expr res_ty)
-
-tcMonoExpr (HsBracket brack loc) res_ty
- = addSrcLoc loc $
- getStage `thenM` \ level ->
- case bracketOK level of {
- Nothing -> failWithTc (illegalBracket level) ;
- Just next_level ->
-
- -- Typecheck expr to make sure it is valid,
- -- but throw away the results. We'll type check
- -- it again when we actually use it.
- newMutVar [] `thenM` \ pending_splices ->
- getLIEVar `thenM` \ lie_var ->
-
- setStage (Brack next_level pending_splices lie_var) (
- getLIE (tcBracket brack)
- ) `thenM` \ (meta_ty, lie) ->
- tcSimplifyBracket lie `thenM_`
-
- unifyTauTy res_ty meta_ty `thenM_`
-
- -- Return the original expression, not the type-decorated one
- readMutVar pending_splices `thenM` \ pendings ->
- returnM (HsBracketOut brack pendings)
- }
-
-tcMonoExpr (HsReify (Reify flavour name)) res_ty
- = addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $
- tcMetaTy tycon_name `thenM` \ reify_ty ->
- unifyTauTy res_ty reify_ty `thenM_`
- returnM (HsReify (ReifyOut flavour name))
- where
- tycon_name = case flavour of
- ReifyDecl -> DsMeta.decTyConName
- ReifyType -> DsMeta.typTyConName
- ReifyFixity -> pprPanic "tcMonoExpr: cant do reifyFixity yet" (ppr name)
-#endif GHCI
+tc_expr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty
+tc_expr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty
+ ; return (unLoc e) }
+#endif /* GHCI */
\end{code}
%************************************************************************
\begin{code}
-tcMonoExpr other _ = pprPanic "tcMonoExpr" (ppr other)
+tc_expr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
\begin{code}
-tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
- -> TcType -- Expected result type of application
- -> TcM TcExpr -- Translated fun and args
+tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args
+ -> Expected TcRhoType -- Expected result type of application
+ -> TcM (HsExpr TcId) -- Translated fun and args
-tcApp (HsApp e1 e2) args res_ty
+tcApp (L _ (HsApp e1 e2)) args res_ty
= tcApp e1 (e2:args) res_ty -- Accumulate the arguments
tcApp fun args res_ty
- = -- First type-check the function
- tcExpr_id fun `thenM` \ (fun', fun_ty) ->
-
- addErrCtxt (wrongArgsCtxt "too many" fun args) (
- traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_`
- split_fun_ty fun_ty (length args)
- ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
-
- -- Now typecheck the args
- mappM (tcArg fun)
- (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
-
- -- Unify with expected result after type-checking the args
- -- so that the info from args percolates to actual_result_ty.
- -- This is when we might detect a too-few args situation.
- -- (One can think of cases when the opposite order would give
- -- a better error message.)
- addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
- (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
-
- returnM (co_fn <$> foldl HsApp fun' args')
-
+ = do { (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 }
+
+
+ ; case res_ty of
+ Check _ -> do -- Connect to result type first
+ -- See Note [Push result type in]
+ { co_fn <- tcResult fun args res_ty actual_res_ty
+ ; the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; traceTc (text "tcApp: check" <+> vcat [ppr fun <+> ppr args,
+ ppr the_app', ppr actual_res_ty])
+ ; returnM (co_fn <$> the_app') }
+
+ Infer _ -> do -- Type check args first, then
+ -- refine result type, then do tcResult
+ { the_app' <- tcArgs fun fun' args expected_arg_tys
+ ; subst <- refineTyVars fun_tvs
+ ; let actual_res_ty' = substTy subst actual_res_ty
+ ; co_fn <- tcResult fun args res_ty actual_res_ty'
+ ; traceTc (text "tcApp: infer" <+> vcat [ppr fun <+> ppr args, ppr the_app',
+ ppr actual_res_ty, ppr actual_res_ty'])
+ ; returnM (co_fn <$> the_app') }
+ }
+
+-- Note [Push result type in]
+--
+-- Unify with expected result before (was: after) type-checking the args
+-- so that the info from res_ty (was: args) percolates to args (was actual_res_ty).
+-- This is when we might detect a too-few args situation.
+-- (One can think of cases when the opposite order would give
+-- a better error message.)
+-- [March 2003: I'm experimenting with putting this first. Here's an
+-- example where it actually makes a real difference
+-- class C t a b | t a -> b
+-- instance C Char a Bool
+--
+-- data P t a = forall b. (C t a b) => MkP b
+-- data Q t = MkQ (forall a. P t a)
+-- f1, f2 :: Q Char;
+-- f1 = MkQ (MkP True)
+-- f2 = MkQ (MkP True :: forall a. P Char a)
+--
+-- With the change, f1 will type-check, because the 'Char' info from
+-- the signature is propagated into MkQ's argument. With the check
+-- in the other order, the extra signature in f2 is reqd.]
+
+----------------
+tcFun :: LHsExpr Name -> TcM (LHsExpr TcId, [TcTyVar], TcRhoType)
+-- Instantiate the function, returning the type variables used
+-- If the function isn't simple, infer its type, and return no
+-- type variables
+tcFun (L loc (HsVar f)) = setSrcSpan loc $ do
+ { (fun', tvs, fun_tau) <- tcId f
+ ; return (L loc fun', tvs, fun_tau) }
+tcFun fun = do { (fun', fun_tau) <- tcInfer (tcMonoExpr fun)
+ ; return (fun', [], fun_tau) }
+
+----------------
+tcArgs :: LHsExpr Name -- The function (for error messages)
+ -> LHsExpr TcId -- The function (to build into result)
+ -> [LHsExpr Name] -> [TcSigmaType] -- Actual arguments and expected arg types
+ -> TcM (HsExpr TcId) -- Resulting application
+
+tcArgs fun fun' args expected_arg_tys
+ = do { args' <- mappM (tcArg fun) (zip3 args expected_arg_tys [1..])
+ ; return (unLoc (foldl mkHsApp fun' args')) }
+
+tcArg :: LHsExpr Name -- The function (for error messages)
+ -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (LHsExpr TcId) -- Resulting argument
+tcArg fun (arg, ty, arg_no) = addErrCtxt (funAppCtxt fun arg arg_no)
+ (tcCheckSigma arg ty)
+
+----------------
+tcResult fun args res_ty actual_res_ty
+ = addErrCtxtM (checkArgsCtxt fun args res_ty actual_res_ty)
+ (tcSubExp res_ty actual_res_ty)
+
+----------------
-- If an error happens we try to figure out whether the
-- function has been given too many or too few arguments,
--- and say so
-checkArgsCtxt fun args expected_res_ty actual_res_ty tidy_env
+-- and say so.
+-- The ~(Check...) is because in the Infer case the tcSubExp
+-- definitely won't fail, so we can be certain we're in the Check branch
+checkArgsCtxt fun args (Infer _) actual_res_ty tidy_env
+ = return (tidy_env, ptext SLIT("Urk infer"))
+
+checkArgsCtxt fun args (Check expected_res_ty) actual_res_ty tidy_env
= zonkTcType expected_res_ty `thenM` \ exp_ty' ->
zonkTcType actual_res_ty `thenM` \ act_ty' ->
let
| otherwise = appCtxt fun args
in
returnM (env2, message)
-
-
-split_fun_ty :: TcType -- The type of the function
- -> Int -- Number of arguments
- -> TcM ([TcType], -- Function argument types
- TcType) -- Function result types
-
-split_fun_ty fun_ty 0
- = returnM ([], fun_ty)
-
-split_fun_ty fun_ty n
- = -- Expect the function to have type A->B
- unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) ->
- split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) ->
- returnM (arg_ty:arg_tys, final_res_ty)
-\end{code}
-
-\begin{code}
-tcArg :: RenamedHsExpr -- The function (for error messages)
- -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type
- -> TcM TcExpr -- Resulting argument and LIE
-
-tcArg the_fun (arg, expected_arg_ty, arg_no)
- = addErrCtxt (funAppCtxt the_fun arg arg_no) $
- tcExpr arg expected_arg_ty
\end{code}
b) perhaps fewer separated lambdas
\begin{code}
-tcId :: Name -> TcM (TcExpr, TcType)
-tcId name -- Look up the Id and instantiate its type
- = tcLookupIdLvl name `thenM` \ (id, bind_lvl) ->
+tcId :: Name -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ -- Return the type variables at which the function
+ -- is instantiated, as well as the translated variable and its type
+
+tcId id_name -- Look up the Id and instantiate its type
+ = tcLookup id_name `thenM` \ thing ->
+ case thing of {
+ AGlobal (ADataCon con) -- Similar, but instantiate the stupid theta too
+ -> do { (expr, tvs, tau) <- instantiate (dataConWrapId con)
+ ; tcInstStupidTheta con (mkTyVarTys tvs)
+ -- Remember to chuck in the constraints from the "silly context"
+ ; return (expr, tvs, tau) }
+
+ ; AGlobal (AnId id) -> instantiate id
+ -- A global cannot possibly be ill-staged
+ -- nor does it need the 'lifting' treatment
+
+ ; ATcId id th_level proc_level
+ -> do { checkProcLevel id proc_level
+ ; tc_local_id id th_level }
+
+ -- THis
+ ; other -> failWithTc (ppr other <+> ptext SLIT("used where a value identifer was expected"))
+ }
+ where
- -- Check for cross-stage lifting
-#ifdef GHCI
- getStage `thenM` \ use_stage ->
- case use_stage of
- Brack use_lvl ps_var lie_var
- | use_lvl > bind_lvl && not (isExternalName name)
- -> -- E.g. \x -> [| h x |]
- -- We must behave as if the reference to x was
+#ifndef GHCI
+ tc_local_id id th_bind_lvl -- Non-TH case
+ = instantiate id
+
+#else /* GHCI and TH is on */
+ tc_local_id id th_bind_lvl -- TH case
+ = -- Check for cross-stage lifting
+ getStage `thenM` \ use_stage ->
+ case use_stage of
+ Brack use_lvl ps_var lie_var
+ | use_lvl > th_bind_lvl
+ -> if isExternalName id_name then
+ -- Top-level identifiers in this module,
+ -- (which have External Names)
+ -- are just like the imported case:
+ -- no need for the 'lifting' treatment
+ -- E.g. this is fine:
+ -- f x = x
+ -- g y = [| f 3 |]
+ -- But we do need to put f into the keep-alive
+ -- set, because after desugaring the code will
+ -- only mention f's *name*, not f itself.
+ keepAliveTc id_name `thenM_`
+ instantiate id
+
+ else -- Nested identifiers, such as 'x' in
+ -- E.g. \x -> [| h x |]
+ -- We must behave as if the reference to x was
-- h $(lift x)
-- We use 'x' itself as the splice proxy, used by
- -- the desugarer to stitch it all back together
- -- NB: isExernalName is true of top level things,
- -- and false of nested bindings
-
- let
- id_ty = idType id
- in
- checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
- -- If x is polymorphic, its occurrence sites might
- -- have different instantiations, so we can't use plain
- -- 'x' as the splice proxy name. I don't know how to
- -- solve this, and it's probably unimportant, so I'm
- -- just going to flag an error for now
-
- setLIEVar lie_var (
- newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
- -- Put the 'lift' constraint into the right LIE
-
- -- Update the pending splices
- readMutVar ps_var `thenM` \ ps ->
- writeMutVar ps_var ((name, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_`
-
- returnM (HsVar id, id_ty))
-
- other ->
- let
- use_lvl = metaLevel use_stage
- in
- checkTc (wellStaged bind_lvl use_lvl)
- (badStageErr id bind_lvl use_lvl) `thenM_`
-#endif
- -- This is the bit that handles the no-Template-Haskell case
- case isDataConWrapId_maybe id of
- Nothing -> loop (HsVar id) (idType id)
- Just data_con -> inst_data_con id data_con
-
- where
- orig = OccurrenceOf name
-
- loop (HsVar fun_id) fun_ty
+ -- the desugarer to stitch it all back together.
+ -- If 'x' occurs many times we may get many identical
+ -- bindings of the same splice proxy, but that doesn't
+ -- matter, although it's a mite untidy.
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((id_name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
+
+ returnM (HsVar id, [], id_ty))
+
+ other ->
+ checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
+ instantiate id
+#endif /* GHCI */
+
+ instantiate :: TcId -> TcM (HsExpr TcId, [TcTyVar], TcRhoType)
+ instantiate fun_id = loop (HsVar fun_id) [] (idType fun_id)
+
+ loop (HsVar fun_id) tvs fun_ty
| want_method_inst fun_ty
- = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ = tcInstType fun_ty `thenM` \ (tyvars, theta, tau) ->
newMethodWithGivenTy orig fun_id
(mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
- loop (HsVar meth_id) tau
+ loop (HsVar meth_id) (tvs ++ tyvars) tau
- loop fun fun_ty
+ loop fun tvs fun_ty
| isSigmaTy fun_ty
- = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
- loop (inst_fn fun) tau
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, new_tvs, tau) ->
+ loop (inst_fn <$> fun) (tvs ++ new_tvs) tau
| otherwise
- = returnM (fun, fun_ty)
+ = returnM (fun, tvs, fun_ty)
- want_method_inst fun_ty
- | opt_NoMethodSharing = False
- | otherwise = case tcSplitSigmaTy fun_ty of
- (_,[],_) -> False -- Not overloaded
- (_,theta,_) -> not (any isLinearPred theta)
- -- This is a slight hack.
+ -- Hack Alert (want_method_inst)!
-- If f :: (%x :: T) => Int -> Int
-- Then if we have two separate calls, (f 3, f 4), we cannot
-- make a method constraint that then gets shared, thus:
-- because that loses the linearity of the constraint.
-- The simplest thing to do is never to construct a method constraint
-- in the first place that has a linear implicit parameter in it.
+ want_method_inst fun_ty
+ | opt_NoMethodSharing = False
+ | otherwise = case tcSplitSigmaTy fun_ty of
+ (_,[],_) -> False -- Not overloaded
+ (_,theta,_) -> not (any isLinearPred theta)
- -- We treat data constructors differently, because we have to generate
- -- constraints for their silly theta, which no longer appears in
- -- the type of dataConWrapId. It's dual to TcPat.tcConstructor
- inst_data_con id data_con
- = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
- extendLIEs ex_dicts `thenM_`
- returnM (mkHsDictApp (mkHsTyApp (HsVar id) ty_args) (map instToId ex_dicts),
- mkFunTys arg_tys result_ty)
-\end{code}
-
-Typecheck expression which in most cases will be an Id.
-The expression can return a higher-ranked type, such as
- (forall a. a->a) -> Int
-so we must create a HoleTyVarTy to pass in as the expected tyvar.
-
-\begin{code}
-tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, TcType)
-tcExpr_id (HsVar name) = tcId name
-tcExpr_id expr = newHoleTyVarTy `thenM` \ id_ty ->
- tcMonoExpr expr id_ty `thenM` \ expr' ->
- readHoleResult id_ty `thenM` \ id_ty' ->
- returnM (expr', id_ty')
+ orig = OccurrenceOf id_name
\end{code}
-
%************************************************************************
%* *
\subsection{Record bindings}
tcRecordBinds
:: TyCon -- Type constructor for the record
-> [TcType] -- Args of this type constructor
- -> RenamedRecordBinds
- -> TcM TcRecordBinds
+ -> HsRecordBinds Name
+ -> TcM (HsRecordBinds TcId)
tcRecordBinds tycon ty_args rbinds
= mappM do_bind rbinds
where
- tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
+ tenv = zipTopTvSubst (tyConTyVars tycon) ty_args
- do_bind (field_lbl_name, rhs)
- = addErrCtxt (fieldCtxt field_lbl_name) $
- tcLookupId field_lbl_name `thenM` \ sel_id ->
+ do_bind (L loc field_lbl, rhs)
+ = addErrCtxt (fieldCtxt field_lbl) $
let
- field_lbl = recordSelectorFieldLabel sel_id
- field_ty = substTy tenv (fieldLabelType field_lbl)
+ field_ty = tyConFieldType tycon field_lbl
+ field_ty' = substTy tenv field_ty
in
+ tcCheckSigma rhs field_ty' `thenM` \ rhs' ->
+ tcLookupId field_lbl `thenM` \ sel_id ->
ASSERT( isRecordSelector sel_id )
+ returnM (L loc sel_id, rhs')
+
+tyConFieldType :: TyCon -> FieldLabel -> Type
+tyConFieldType tycon field_lbl
+ = case [ty | (f,ty,_) <- tyConFields tycon, f == field_lbl] of
+ (ty:other) -> ASSERT( null other) ty
-- This lookup and assertion will surely succeed, because
-- we check that the fields are indeed record selectors
-- before calling tcRecordBinds
- ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl )
- -- The caller of tcRecordBinds has already checked
- -- that all the fields come from the same type
-
- tcExpr rhs field_ty `thenM` \ rhs' ->
-
- returnM (sel_id, rhs')
badFields rbinds data_con
= filter (not . (`elem` field_names)) (recBindFields rbinds)
where
- field_names = map fieldLabelName (dataConFieldLabels data_con)
+ field_names = dataConFieldLabels data_con
-checkMissingFields :: DataCon -> RenamedRecordBinds -> TcM ()
+checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM ()
checkMissingFields data_con rbinds
| null field_labels -- Not declared as a record;
-- But C{} is still valid if no strict fields
missing_s_fields
= [ fl | (fl, str) <- field_info,
isMarkedStrict str,
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
missing_ns_fields
= [ fl | (fl, str) <- field_info,
not (isMarkedStrict str),
- not (fieldLabelName fl `elem` field_names_used)
+ not (fl `elem` field_names_used)
]
field_names_used = recBindFields rbinds
field_labels
field_strs
- field_strs = dropList ex_theta (dataConStrictMarks data_con)
- -- The 'drop' is because dataConStrictMarks
- -- includes the existential dictionaries
- (_, _, _, ex_theta, _, _) = dataConSig data_con
+ field_strs = dataConStrictMarks data_con
\end{code}
%************************************************************************
%* *
-\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions}
%* *
%************************************************************************
\begin{code}
-tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr]
+tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId]
-tcMonoExprs [] [] = returnM []
-tcMonoExprs (expr:exprs) (ty:tys)
- = tcMonoExpr expr ty `thenM` \ expr' ->
- tcMonoExprs exprs tys `thenM` \ exprs' ->
+tcCheckRhos [] [] = returnM []
+tcCheckRhos (expr:exprs) (ty:tys)
+ = tcCheckRho expr ty `thenM` \ expr' ->
+ tcCheckRhos exprs tys `thenM` \ exprs' ->
returnM (expr':exprs')
\end{code}
Overloaded literals.
\begin{code}
-tcLit :: HsLit -> TcType -> TcM TcExpr
-tcLit (HsLitLit s _) res_ty
- = tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
- newDicts (LitLitOrigin (unpackFS s))
- [mkClassPred cCallableClass [res_ty]] `thenM` \ dicts ->
- extendLIEs dicts `thenM_`
- returnM (HsLit (HsLitLit s res_ty))
-
+tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId)
tcLit lit res_ty
- = unifyTauTy res_ty (hsLitType lit) `thenM_`
+ = zapExpectedTo res_ty (hsLitType lit) `thenM_`
returnM (HsLit lit)
\end{code}
arithSeqCtxt expr
= hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-
-badStageErr id bind_lvl use_lvl
- = ptext SLIT("Stage error:") <+> quotes (ppr id) <+>
- hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
- ptext SLIT("but used at stage") <+> ppr use_lvl]
-
parrSeqCtxt expr
= hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
caseScrutCtxt expr
= hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-exprSigCtxt expr
- = hang (ptext SLIT("When checking the type signature of the expression:"))
- 4 (ppr expr)
-
exprCtxt expr
= hang (ptext SLIT("In the expression:")) 4 (ppr expr)
predCtxt expr
= hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-illegalBracket level
- = ptext SLIT("Illegal bracket at level") <+> ppr level
-
appCtxt fun args
= ptext SLIT("In the application") <+> quotes (ppr the_app)
where
- the_app = foldl HsApp fun args -- Used in error messages
-
-lurkingRank2Err fun fun_ty
- = hang (hsep [ptext SLIT("Illegal use of"), quotes (ppr fun)])
- 4 (vcat [ptext SLIT("It is applied to too few arguments"),
- ptext SLIT("so that the result type has for-alls in it:") <+> ppr fun_ty])
+ the_app = foldl mkHsApp fun args -- Used in error messages
badFieldsUpd rbinds
= hang (ptext SLIT("No constructor has all these fields:"))
header = ptext SLIT("Constructor") <+> quotes (ppr con) <+>
ptext SLIT("does not have the required strict field(s)")
-
missingFields :: DataCon -> [FieldLabel] -> SDoc
missingFields con fields
= ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:")
<+> pprWithCommas ppr fields
-polySpliceErr :: Id -> SDoc
-polySpliceErr id
- = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
-
wrongArgsCtxt too_many_or_few fun args
= hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun)
<+> ptext SLIT("is applied to") <+> text too_many_or_few
<+> ptext SLIT("arguments in the call"))
4 (parens (ppr the_app))
where
- the_app = foldl HsApp fun args -- Used in error messages
+ the_app = foldl mkHsApp fun args -- Used in error messages
+
+#ifdef GHCI
+polySpliceErr :: Id -> SDoc
+polySpliceErr id
+ = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
+#endif
\end{code}
projects / ghc-hetmet.git / blobdiff