\section[TcExpr]{Typecheck an expression}
\begin{code}
-module TcExpr ( tcExpr, tcMonoExpr, tcId ) where
+module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where
#include "HsVersions.h"
-import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
- HsMatchContext(..), HsDoContext(..),
- mkMonoBind
- )
-import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy, mkHsDictApp, mkHsTyApp )
-
-import TcMonad
-import TcUnify ( tcSubExp, tcGen, (<$>),
- unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy,
- unifyTupleTy )
-import BasicTypes ( RecFlag(..), isMarkedStrict )
+#ifdef GHCI /* Only if bootstrapped */
+import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
+import Id ( Id )
+import TcType ( isTauTy )
+import TcEnv ( checkWellStaged )
+import HsSyn ( nlHsApp )
+import qualified DsMeta
+#endif
+
+import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
+ HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar )
+import TcHsSyn ( hsLitType, mkHsDictApp, mkHsTyApp, (<$>) )
+import TcRnMonad
+import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
+ unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy )
+import BasicTypes ( isMarkedStrict )
import Inst ( InstOrigin(..),
- LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs,
newOverloadedLit, newMethodFromName, newIPDict,
- newDicts, newMethodWithGivenTy,
+ newDicts, newMethodWithGivenTy,
instToId, tcInstCall, tcInstDataCon
)
import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe,
- tcLookupTyCon, tcLookupDataCon, tcLookupId
+import TcEnv ( tcLookup, tcLookupId, checkProcLevel,
+ tcLookupDataCon, tcLookupGlobalId
)
-import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts )
-import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
+import TcArrows ( tcProc )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) )
+import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
import TcPat ( badFieldCon )
-import TcSimplify ( tcSimplifyIPs )
-import TcMType ( tcInstTyVars, tcInstType, newHoleTyVarTy, zapToType,
- newTyVarTy, newTyVarTys, zonkTcType, readHoleResult )
+import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType )
import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
- isSigmaTy, mkFunTy, mkAppTy, mkFunTys,
- mkTyConApp, mkClassPred, tcFunArgTy,
- tyVarsOfTypes, isLinearPred,
- liftedTypeKind, openTypeKind, mkArrowKind,
- tcSplitSigmaTy, tcTyConAppTyCon,
- tidyOpenType
+ isSigmaTy, mkFunTy, mkFunTys,
+ mkTyConApp, tyVarsOfTypes, isLinearPred,
+ tcSplitSigmaTy, tidyOpenType
)
+import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
+
import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( idType, recordSelectorFieldLabel, isRecordSelector, isDataConWrapId_maybe )
-import DataCon ( dataConFieldLabels, dataConSig,
- dataConStrictMarks
- )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId )
import Name ( Name )
-import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
+import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons )
import Subst ( mkTopTyVarSubst, substTheta, substTy )
import VarSet ( emptyVarSet, elemVarSet )
-import TysWiredIn ( boolTy, mkListTy, mkPArrTy )
-import PrelNames ( cCallableClassName,
- cReturnableClassName,
- enumFromName, enumFromThenName,
+import TysWiredIn ( boolTy )
+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, LIE) -- Generalised expr with expected type, and LIE
+-- 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
- = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenNF_Tc_`
+tcCheckSigma expr expected_ty
+ = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
tc_expr' expr expected_ty
-tc_expr' expr expected_ty
- | not (isSigmaTy expected_ty) -- Monomorphic case
- = tcMonoExpr expr expected_ty
+tc_expr' expr sigma_ty
+ | isSigmaTy sigma_ty
+ = tcGen sigma_ty emptyVarSet (
+ \ rho_ty -> tcCheckRho expr rho_ty
+ ) `thenM` \ (gen_fn, expr') ->
+ returnM (L (getLoc expr') (gen_fn <$> unLoc expr'))
- | otherwise
- = tcGen expected_ty emptyVarSet (
- tcMonoExpr expr
- ) `thenTc` \ (gen_fn, expr', lie) ->
- returnTc (gen_fn <$> expr', lie)
+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)) = addSrcSpan loc $
+ do { (e,ty) <- tcId name; return (L loc e, ty)}
+tcInferRho expr = newHole `thenM` \ hole ->
+ tcMonoExpr expr (Infer hole) `thenM` \ expr' ->
+ readMutVar hole `thenM` \ rho_ty ->
+ returnM (expr', rho_ty)
+\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, LIE)
+ -> TcM (LHsExpr TcId)
+
+tcMonoExpr (L loc expr) res_ty
+ = addSrcSpan loc (do { expr' <- tc_expr expr res_ty
+ ; return (L loc expr') })
-tcMonoExpr (HsVar name) res_ty
- = tcId name `thenNF_Tc` \ (expr', lie1, id_ty) ->
- tcSubExp res_ty id_ty `thenTc` \ (co_fn, lie2) ->
- returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
+tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
+tc_expr (HsVar name) res_ty
+ = tcId name `thenM` \ (expr', id_ty) ->
+ tcSubExp res_ty id_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> expr')
-tcMonoExpr (HsIPVar ip) res_ty
+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 `thenNF_Tc` \ ip_ty ->
- newIPDict (IPOcc ip) ip ip_ty `thenNF_Tc` \ (ip', inst) ->
- tcSubExp res_ty ip_ty `thenTc` \ (co_fn, lie) ->
- returnNF_Tc (co_fn <$> HsIPVar ip', lie `plusLIE` unitLIE inst)
+ newTyVarTy argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
+ newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
+ extendLIE inst `thenM_`
+ tcSubExp res_ty ip_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> HsIPVar ip')
\end{code}
%************************************************************************
\begin{code}
-tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = tcAddErrCtxt (exprSigCtxt in_expr) $
- tcHsSigType ExprSigCtxt poly_ty `thenTc` \ sig_tc_ty ->
- tcExpr expr sig_tc_ty `thenTc` \ (expr', lie1) ->
-
- -- 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 `thenNF_Tc` \ (inst_fn, lie2, inst_sig_ty) ->
- tcSubExp res_ty inst_sig_ty `thenTc` \ (co_fn, lie3) ->
-
- returnTc (co_fn <$> inst_fn expr', lie1 `plusLIE` lie2 `plusLIE` lie3)
-
-tcMonoExpr (HsType ty) res_ty
+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 <$> unLoc expr')
+ -- ToDo: nasty unLoc
+
+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
+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' ->
+ newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr ->
+ returnM (unLoc lit_expr) -- ToDo: nasty unLoc
-tcMonoExpr (NegApp expr neg_name) res_ty
- = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
+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
- = tcMatchLambda match res_ty `thenTc` \ (match',lie) ->
- returnTc (HsLam match', lie)
+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 `thenTc` \ (op', lie1, op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
- tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2) ->
- tcAddErrCtxt (exprCtxt in_expr) $
- tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
- returnTc (co_fn <$> SectionL arg1' op', lie1 `plusLIE` lie2 `plusLIE` lie3)
+tc_expr in_expr@(SectionL arg1 op) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- 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 ->
+ returnM (co_fn <$> SectionL arg1' op')
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcMonoExpr in_expr@(SectionR op arg2) res_ty
- = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
- tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2) ->
- tcAddErrCtxt (exprCtxt in_expr) $
- tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
- returnTc (co_fn <$> SectionR op' arg2', lie1 `plusLIE` lie2 `plusLIE` lie3)
+tc_expr in_expr@(SectionR op arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- 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 ->
+ returnM (co_fn <$> SectionR op' arg2')
-- equivalent to (op e1) e2:
-tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty
- = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
- split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
- tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2a) ->
- tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2b) ->
- tcAddErrCtxt (exprCtxt in_expr) $
- tcSubExp res_ty op_res_ty `thenTc` \ (co_fn, lie3) ->
- returnTc (OpApp arg1' op' fix arg2',
- lie1 `plusLIE` lie2a `plusLIE` lie2b `plusLIE` lie3)
+tc_expr in_expr@(OpApp arg1 op fix arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- 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) $
+ tcSubExp res_ty op_res_ty `thenM` \ co_fn ->
+ returnM (OpApp arg1' op' fix arg2')
\end{code}
-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
-
- = getDOptsTc `thenNF_Tc` \ dflags ->
-
- 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."])
- `thenTc_`
-
- -- Get the callable and returnable classes.
- tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass ->
- tcLookupClass cReturnableClassName `thenNF_Tc` \ cReturnableClass ->
- tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon ->
- let
- new_arg_dict (arg, arg_ty)
- = newDicts (CCallOrigin (unpackFS lbl) (Just arg))
- [mkClassPred cCallableClass [arg_ty]] `thenNF_Tc` \ arg_dicts ->
- returnNF_Tc 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 `thenNF_Tc` \ arg_tys ->
- tcMonoExprs args arg_tys `thenTc` \ (args', args_lie) ->
-
- -- 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 `thenNF_Tc` \ result_ty ->
- let
- io_result_ty = mkTyConApp ioTyCon [result_ty]
- in
- unifyTauTy res_ty io_result_ty `thenTc_`
-
- -- Construct the extra insts, which encode the
- -- constraints on the argument and result types.
- mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenNF_Tc` \ ccres_dict ->
- returnTc (HsCCall lbl args' may_gc is_casm io_result_ty,
- mkLIE (ccres_dict ++ concat ccarg_dicts_s) `plusLIE` args_lie)
-\end{code}
-
-\begin{code}
-tcMonoExpr (HsSCC lbl expr) res_ty
- = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
- returnTc (HsSCC lbl expr', lie)
-
-tcMonoExpr (HsLet binds expr) res_ty
+tc_expr (HsLet binds (L loc expr)) res_ty
= tcBindsAndThen
- combiner
+ glue
binds -- Bindings to check
- tc_expr `thenTc` \ (expr', lie) ->
- returnTc (expr', lie)
+ (tc_expr expr res_ty)
where
- tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
- returnTc (expr', lie)
- combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr
+ glue bind expr = HsLet [bind] (L loc expr)
-tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (caseCtxt in_expr) $
+tc_expr in_expr@(HsCase scrut matches) res_ty
+ = addErrCtxt (caseCtxt in_expr) $
-- Typecheck the case alternatives first.
-- The case patterns tend to give good type info to use
-- 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 `thenTc` \ (scrut_ty, matches', lie2) ->
+ tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') ->
- tcAddErrCtxt (caseScrutCtxt scrut) (
- tcMonoExpr scrut scrut_ty
- ) `thenTc` \ (scrut',lie1) ->
+ addErrCtxt (caseScrutCtxt scrut) (
+ tcCheckRho scrut scrut_ty
+ ) `thenM` \ scrut' ->
- returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
+ returnM (HsCase scrut' matches')
+ where
+ match_ctxt = MC { mc_what = CaseAlt,
+ mc_body = tcMonoExpr }
-tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (predCtxt pred) (
- tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
+tc_expr (HsIf pred b1 b2) res_ty
+ = addErrCtxt (predCtxt pred) (
+ tcCheckRho pred boolTy ) `thenM` \ pred' ->
- zapToType res_ty `thenTc` \ res_ty' ->
+ zapExpectedType res_ty openTypeKind `thenM` \ res_ty' ->
-- C.f. the call to zapToType in TcMatches.tcMatches
- tcMonoExpr b1 res_ty' `thenTc` \ (b1',lie2) ->
- tcMonoExpr b2 res_ty' `thenTc` \ (b2',lie3) ->
- returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3))
-\end{code}
+ tcCheckRho b1 res_ty' `thenM` \ b1' ->
+ tcCheckRho b2 res_ty' `thenM` \ b2' ->
+ returnM (HsIf pred' b1' b2')
-\begin{code}
-tcMonoExpr expr@(HsDo do_or_lc stmts method_names _ src_loc) res_ty
- = tcAddSrcLoc src_loc (tcDoStmts do_or_lc stmts method_names src_loc res_ty)
-\end{code}
+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')
-\begin{code}
-tcMonoExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
- = unifyListTy res_ty `thenTc` \ elt_ty ->
- mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) ->
- returnTc (ExplicitList elt_ty exprs', plusLIEs lies)
+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
- = tcAddErrCtxt (listCtxt expr) $
- tcMonoExpr expr elt_ty
+ = addErrCtxt (listCtxt expr) $
+ tcCheckRho expr elt_ty
-tcMonoExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
- = unifyPArrTy res_ty `thenTc` \ elt_ty ->
- mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) ->
- returnTc (ExplicitPArr elt_ty exprs', plusLIEs lies)
+tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+ = zapToPArrTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitPArr elt_ty exprs')
where
tc_elt elt_ty expr
- = tcAddErrCtxt (parrCtxt expr) $
- tcMonoExpr expr elt_ty
-
-tcMonoExpr (ExplicitTuple exprs boxity) res_ty
- = unifyTupleTy boxity (length exprs) res_ty `thenTc` \ arg_tys ->
- mapAndUnzipTc (\ (expr, arg_ty) -> tcMonoExpr expr arg_ty)
- (exprs `zip` arg_tys) -- we know they're of equal length.
- `thenTc` \ (exprs', lies) ->
- returnTc (ExplicitTuple exprs' boxity, plusLIEs lies)
-
-tcMonoExpr expr@(RecordCon con_name rbinds) res_ty
- = tcAddErrCtxt (recordConCtxt expr) $
- tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+ = addErrCtxt (parrCtxt expr) $
+ tcCheckRho expr elt_ty
+
+tc_expr (ExplicitTuple exprs boxity) res_ty
+ = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
+ tcCheckRhos exprs arg_tys `thenM` \ exprs' ->
+ returnM (ExplicitTuple exprs' boxity)
+
+tc_expr (HsProc pat cmd) res_ty
+ = tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
+ returnM (HsProc pat' cmd')
+\end{code}
+
+%************************************************************************
+%* *
+ Record construction and update
+%* *
+%************************************************************************
+
+\begin{code}
+tc_expr expr@(RecordCon con@(L _ con_name) rbinds) res_ty
+ = addErrCtxt (recordConCtxt expr) $
+ 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 `thenTc_`
+ 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 `thenTc` \ data_con ->
+ tcLookupDataCon con_name `thenM` \ data_con ->
let
bad_fields = badFields rbinds data_con
in
if notNull bad_fields then
- mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_`
- failTc -- Fail now, because tcRecordBinds will crash on a bad field
+ mappM (addErrTc . badFieldCon data_con) bad_fields `thenM_`
+ failM -- Fail now, because tcRecordBinds will crash on a bad field
else
-- Typecheck the record bindings
- tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' ->
- let
- (missing_s_fields, missing_fields) = missingFields rbinds data_con
- in
- checkTcM (null missing_s_fields)
- (mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_`
- returnNF_Tc ()) `thenNF_Tc_`
- doptsTc Opt_WarnMissingFields `thenNF_Tc` \ warn ->
- checkTcM (not (warn && notNull missing_fields))
- (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_`
- returnNF_Tc ()) `thenNF_Tc_`
+ -- Check for missing fields
+ checkMissingFields data_con rbinds `thenM_`
- returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie)
+ getSrcSpanM `thenM` \ loc ->
+ 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
- = tcAddErrCtxt (recordUpdCtxt expr) $
+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 = [field_name | (field_name, _, _) <- rbinds]
+ field_names = map fst rbinds
in
- mapNF_Tc tcLookupGlobal_maybe field_names `thenNF_Tc` \ 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 = [ addSrcSpan loc $ addErrTc (notSelector field_name)
+ | (L loc field_name, sel_id) <- field_names `zip` sel_ids,
+ not (isRecordSelector sel_id) -- Excludes class ops
]
in
- checkTcM (null bad_guys) (listNF_Tc bad_guys `thenNF_Tc_` failTc) `thenTc_`
+ checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_`
-- STEP 1
-- 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
+ sel_id : _ = sel_ids
+ field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if
+ tycon = fieldLabelTyCon field_lbl -- it's not a field label
data_cons = tyConDataCons tycon
tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars VanillaTv tycon_tyvars `thenNF_Tc` \ (_, result_inst_tys, inst_env) ->
+ tcInstTyVars VanillaTv 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) `thenTc_`
+ (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 `thenTc_`
- tcRecordBinds tycon result_inst_tys rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ zapExpectedTo res_ty result_record_ty `thenM_`
+ tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' ->
-- STEP 4
-- Use the un-updated fields to find a vector of booleans saying
-- WARNING: this code assumes that all data_cons in a common tycon
-- have FieldLabels abstracted over the same tyvars.
let
- upd_field_lbls = [recordSelectorFieldLabel sel_id | (sel_id, _, _) <- rbinds']
+ upd_field_lbls = map recordSelectorFieldLabel (recBindFields rbinds')
con_field_lbls_s = map dataConFieldLabels data_cons
-- A constructor is only relevant to this process if
common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
mk_inst_ty (tyvar, result_inst_ty)
- | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
+ | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
| otherwise = newTyVarTy liftedTypeKind -- Fresh type
in
- mapNF_Tc mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
+ mappM mk_inst_ty (zip 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 `thenTc` \ (record_expr', record_lie) ->
+ tcCheckRho record_expr record_ty `thenM` \ record_expr' ->
-- STEP 6
-- Figure out the LIE we need. We have to generate some
let
theta' = substTheta inst_env (tyConTheta tycon)
in
- newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts ->
+ newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
-- Phew!
- returnTc (RecordUpdOut record_expr' record_ty result_record_ty rbinds',
- mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie)
+ returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds')
+\end{code}
+
+
+%************************************************************************
+%* *
+ Arithmetic sequences e.g. [a,b..]
+ and their parallel-array counterparts e.g. [: a,b.. :]
+
+%* *
+%************************************************************************
-tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
- = unifyListTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) ->
+\begin{code}
+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 `thenNF_Tc` \ enum_from ->
+ elt_ty enumFromName `thenM` \ enum_from ->
- returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'),
- lie1 `plusLIE` unitLIE enum_from)
+ returnM (ArithSeqOut (nlHsVar enum_from) (From expr'))
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
- = tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+tc_expr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (ArithSeqOrigin seq)
- elt_ty enumFromThenName `thenNF_Tc` \ enum_from_then ->
+ elt_ty enumFromThenName `thenM` \ enum_from_then ->
+
+ returnM (ArithSeqOut (nlHsVar enum_from_then) (FromThen expr1' expr2'))
- returnTc (ArithSeqOut (HsVar (instToId enum_from_then))
- (FromThen expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_then)
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
- = tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+tc_expr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (ArithSeqOrigin seq)
- elt_ty enumFromToName `thenNF_Tc` \ enum_from_to ->
-
- returnTc (ArithSeqOut (HsVar (instToId enum_from_to))
- (FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to)
-
-tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
- = tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyListTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
- tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
+ elt_ty enumFromToName `thenM` \ enum_from_to ->
+
+ returnM (ArithSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+
+tc_expr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ 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 `thenNF_Tc` \ eft ->
+ elt_ty enumFromThenToName `thenM` \ eft ->
- returnTc (ArithSeqOut (HsVar (instToId eft))
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft)
+ returnM (ArithSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
- = tcAddErrCtxt (parrSeqCtxt in_expr) $
- unifyPArrTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToPArrTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
newMethodFromName (PArrSeqOrigin seq)
- elt_ty enumFromToPName `thenNF_Tc` \ enum_from_to ->
-
- returnTc (PArrSeqOut (HsVar (instToId enum_from_to))
- (FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to)
-
-tcMonoExpr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
- = tcAddErrCtxt (parrSeqCtxt in_expr) $
- unifyPArrTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
- tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
+ elt_ty enumFromToPName `thenM` \ enum_from_to ->
+
+ returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+
+tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToPArrTy 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 `thenNF_Tc` \ eft ->
+ elt_ty enumFromThenToPName `thenM` \ eft ->
- returnTc (PArrSeqOut (HsVar (instToId eft))
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft)
+ 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
\end{code}
+
%************************************************************************
%* *
-\subsection{Implicit Parameter bindings}
+ Template Haskell
%* *
%************************************************************************
\begin{code}
-tcMonoExpr (HsWith expr binds is_with) res_ty
- = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) ->
- mapAndUnzip3Tc tcIPBind binds `thenTc` \ (avail_ips, binds', bind_lies) ->
+#ifdef GHCI /* Only if bootstrapped */
+ -- Rename excludes these cases otherwise
+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}
- -- If the binding binds ?x = E, we must now
- -- discharge any ?x constraints in expr_lie
- tcSimplifyIPs avail_ips expr_lie `thenTc` \ (expr_lie', dict_binds) ->
- let
- expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr'
- in
- returnTc (HsWith expr'' binds' is_with, expr_lie' `plusLIE` plusLIEs bind_lies)
-
-tcIPBind (ip, expr)
- = newTyVarTy openTypeKind `thenTc` \ ty ->
- tcGetSrcLoc `thenTc` \ loc ->
- newIPDict (IPBind ip) ip ty `thenNF_Tc` \ (ip', ip_inst) ->
- tcMonoExpr expr ty `thenTc` \ (expr', lie) ->
- returnTc (ip_inst, (ip', expr'), lie)
+
+%************************************************************************
+%* *
+ Catch-all
+%* *
+%************************************************************************
+
+\begin{code}
+tc_expr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
+
%************************************************************************
%* *
\subsection{@tcApp@ typchecks an application}
\begin{code}
-tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
- -> TcType -- Expected result type of application
- -> TcM (TcExpr, LIE) -- 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 `thenTc` \ (fun', lie_fun, fun_ty) ->
+ tcInferRho fun `thenM` \ (fun', fun_ty) ->
- tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
- traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenNF_Tc_`
+ addErrCtxt (wrongArgsCtxt "too many" fun args) (
+ traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_`
split_fun_ty fun_ty (length args)
- ) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
-
- -- Now typecheck the args
- mapAndUnzipTc (tcArg fun)
- (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) ->
+ ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
- -- Unify with expected result after type-checking the args
- -- so that the info from args percolates to actual_result_ty.
+ -- 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_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.)
- tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
- (tcSubExp res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) ->
+ -- [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.]
+
+ addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
+ (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
+
+ -- Now typecheck the args
+ mappM (tcArg fun)
+ (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
- returnTc (co_fn <$> foldl HsApp fun' args',
- lie_res `plusLIE` lie_fun `plusLIE` plusLIEs lie_args_s)
+ returnM (co_fn <$> unLoc (foldl mkHsApp fun' args'))
-- 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
- = zonkTcType expected_res_ty `thenNF_Tc` \ exp_ty' ->
- zonkTcType actual_res_ty `thenNF_Tc` \ act_ty' ->
+-- 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 ~(Check expected_res_ty) actual_res_ty tidy_env
+ = zonkTcType expected_res_ty `thenM` \ exp_ty' ->
+ zonkTcType actual_res_ty `thenM` \ act_ty' ->
let
(env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
(env2, act_ty'') = tidyOpenType env1 act_ty'
| len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args
| otherwise = appCtxt fun args
in
- returnNF_Tc (env2, message)
+ returnM (env2, message)
-split_fun_ty :: TcType -- The type of the function
+split_fun_ty :: TcRhoType -- The type of the function
-> Int -- Number of arguments
-> TcM ([TcType], -- Function argument types
TcType) -- Function result types
split_fun_ty fun_ty 0
- = returnTc ([], fun_ty)
+ = returnM ([], fun_ty)
split_fun_ty fun_ty n
= -- Expect the function to have type A->B
- unifyFunTy fun_ty `thenTc` \ (arg_ty, res_ty) ->
- split_fun_ty res_ty (n-1) `thenTc` \ (arg_tys, final_res_ty) ->
- returnTc (arg_ty:arg_tys, final_res_ty)
+ 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, LIE) -- Resulting argument and LIE
+tcArg :: LHsExpr Name -- The function (for error messages)
+ -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (LHsExpr TcId) -- Resulting argument
tcArg the_fun (arg, expected_arg_ty, arg_no)
- = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
- tcExpr arg expected_arg_ty
+ = addErrCtxt (funAppCtxt the_fun arg arg_no) $
+ tcCheckSigma arg expected_arg_ty
\end{code}
b) perhaps fewer separated lambdas
\begin{code}
-tcId :: Name -> NF_TcM (TcExpr, LIE, TcType)
+tcId :: Name -> TcM (HsExpr TcId, TcRhoType)
tcId name -- Look up the Id and instantiate its type
- = tcLookupId name `thenNF_Tc` \ id ->
- case isDataConWrapId_maybe id of
- Nothing -> loop (HsVar id) emptyLIE (idType id)
- Just data_con -> inst_data_con id data_con
+ = -- First check whether it's a DataCon
+ -- Reason: we must not forget to chuck in the
+ -- constraints from their "silly context"
+ tcLookup name `thenM` \ thing ->
+ case thing of {
+ AGlobal (ADataCon data_con) -> inst_data_con data_con
+ ; AGlobal (AnId id) -> loop (HsVar id) (idType id)
+ -- A global cannot possibly be ill-staged
+ -- nor does it need the 'lifting' treatment
+
+ ; ATcId id th_level proc_level -> tc_local_id id th_level proc_level
+ ; other -> pprPanic "tcId" (ppr name $$ ppr thing)
+ }
where
- orig = OccurrenceOf name
- loop (HsVar fun_id) lie fun_ty
+#ifndef GHCI
+ tc_local_id id th_bind_lvl proc_lvl -- Non-TH case
+ = checkProcLevel id proc_lvl `thenM_`
+ loop (HsVar id) (idType id)
+
+#else /* GHCI and TH is on */
+ tc_local_id id th_bind_lvl proc_lvl -- TH case
+ = checkProcLevel id proc_lvl `thenM_`
+
+ -- 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
+ -> -- E.g. \x -> [| h x |]
+ -- We must behave as if the reference to x was
+
+ -- h $(lift x)
+ -- We use 'x' itself as the splice proxy, used by
+ -- the desugarer to stitch it all back together.
+ -- If 'x' occurs many times we may get many identical
+ -- bindings of the same splice proxy, but that doesn't
+ -- matter, although it's a mite untidy.
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
+
+ returnM (HsVar id, id_ty))
+
+ other ->
+ checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
+ loop (HsVar id) (idType id)
+#endif /* GHCI */
+
+ loop (HsVar fun_id) fun_ty
| want_method_inst fun_ty
- = tcInstType VanillaTv fun_ty `thenNF_Tc` \ (tyvars, theta, tau) ->
+ = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
newMethodWithGivenTy orig fun_id
- (mkTyVarTys tyvars) theta tau `thenNF_Tc` \ meth ->
- loop (HsVar (instToId meth))
- (unitLIE meth `plusLIE` lie) tau
+ (mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
+ loop (HsVar meth_id) tau
- loop fun lie fun_ty
+ loop fun fun_ty
| isSigmaTy fun_ty
- = tcInstCall orig fun_ty `thenNF_Tc` \ (inst_fn, inst_lie, tau) ->
- loop (inst_fn fun) (inst_lie `plusLIE` lie) tau
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
+ loop (inst_fn <$> fun) tau
| otherwise
- = returnNF_Tc (fun, lie, fun_ty)
+ = returnM (fun, 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 `thenNF_Tc` \ (ty_args, ex_dicts, arg_tys, result_ty, stupid_lie, ex_lie, _) ->
- returnNF_Tc (mkHsDictApp (mkHsTyApp (HsVar id) ty_args) ex_dicts,
- stupid_lie `plusLIE` ex_lie,
- 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, LIE, TcType)
-tcExpr_id (HsVar name) = tcId name
-tcExpr_id expr = newHoleTyVarTy `thenNF_Tc` \ id_ty ->
- tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) ->
- readHoleResult id_ty `thenTc` \ id_ty' ->
- returnTc (expr', lie_id, id_ty')
-\end{code}
+ -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs
+ -- It's dual to TcPat.tcConstructor
+ inst_data_con data_con
+ = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
+ extendLIEs ex_dicts `thenM_`
+ getSrcSpanM `thenM` \ loc ->
+ returnM (unLoc (mkHsDictApp (mkHsTyApp (L loc (HsVar (dataConWrapId data_con))) ty_args)
+ (map instToId ex_dicts)),
+ mkFunTys arg_tys result_ty)
+ -- ToDo: nasty loc/unloc stuff here
-
-%************************************************************************
-%* *
-\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
-%* *
-%************************************************************************
-
-\begin{code}
-tcDoStmts PArrComp stmts method_names src_loc res_ty
- = unifyPArrTy res_ty `thenTc` \elt_ty ->
- tcStmts (DoCtxt PArrComp)
- (mkPArrTy, elt_ty) stmts `thenTc` \(stmts', stmts_lie) ->
- returnTc (HsDo PArrComp stmts'
- [] -- Unused
- res_ty src_loc,
- stmts_lie)
-
-tcDoStmts ListComp stmts method_names src_loc res_ty
- = unifyListTy res_ty `thenTc` \ elt_ty ->
- tcStmts (DoCtxt ListComp)
- (mkListTy, elt_ty) stmts `thenTc` \ (stmts', stmts_lie) ->
- returnTc (HsDo ListComp stmts'
- [] -- Unused
- res_ty src_loc,
- stmts_lie)
-
-tcDoStmts DoExpr stmts method_names src_loc res_ty
- = newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ tc_ty ->
- newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty ->
- unifyTauTy res_ty (mkAppTy tc_ty elt_ty) `thenTc_`
-
- tcStmts (DoCtxt DoExpr) (mkAppTy tc_ty, elt_ty) stmts `thenTc` \ (stmts', stmts_lie) ->
-
- -- Build the then and zero methods in case we need them
- -- It's important that "then" and "return" appear just once in the final LIE,
- -- not only for typechecker efficiency, but also because otherwise during
- -- simplification we end up with silly stuff like
- -- then = case d of (t,r) -> t
- -- then = then
- -- where the second "then" sees that it already exists in the "available" stuff.
- --
- mapNF_Tc (newMethodFromName DoOrigin tc_ty) method_names `thenNF_Tc` \ insts ->
-
- returnTc (HsDo DoExpr stmts'
- (map instToId insts)
- res_ty src_loc,
- stmts_lie `plusLIE` mkLIE insts)
+ orig = OccurrenceOf name
\end{code}
-
%************************************************************************
%* *
\subsection{Record bindings}
tcRecordBinds
:: TyCon -- Type constructor for the record
-> [TcType] -- Args of this type constructor
- -> RenamedRecordBinds
- -> TcM (TcRecordBinds, LIE)
+ -> HsRecordBinds Name
+ -> TcM (HsRecordBinds TcId)
tcRecordBinds tycon ty_args rbinds
- = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) ->
- returnTc (rbinds', plusLIEs lies)
+ = mappM do_bind rbinds
where
tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
- do_bind (field_lbl_name, rhs, pun_flag)
- = tcLookupGlobalId field_lbl_name `thenNF_Tc` \ sel_id ->
+ do_bind (L loc field_lbl_name, rhs)
+ = addErrCtxt (fieldCtxt field_lbl_name) $
+ tcLookupId field_lbl_name `thenM` \ sel_id ->
let
field_lbl = recordSelectorFieldLabel sel_id
field_ty = substTy tenv (fieldLabelType field_lbl)
-- The caller of tcRecordBinds has already checked
-- that all the fields come from the same type
- tcExpr rhs field_ty `thenTc` \ (rhs', lie) ->
+ tcCheckSigma rhs field_ty `thenM` \ rhs' ->
- returnTc ((sel_id, rhs', pun_flag), lie)
+ returnM (L loc sel_id, rhs')
badFields rbinds data_con
- = [field_name | (field_name, _, _) <- rbinds,
- not (field_name `elem` field_names)
- ]
+ = filter (not . (`elem` field_names)) (recBindFields rbinds)
where
field_names = map fieldLabelName (dataConFieldLabels data_con)
-missingFields rbinds data_con
- | null field_labels = ([], []) -- Not declared as a record;
- -- But C{} is still valid
- | otherwise
- = (missing_strict_fields, other_missing_fields)
+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
+ = if any isMarkedStrict field_strs then
+ -- Illegal if any arg is strict
+ addErrTc (missingStrictFields data_con [])
+ else
+ returnM ()
+
+ | otherwise -- A record
+ = checkM (null missing_s_fields)
+ (addErrTc (missingStrictFields data_con missing_s_fields)) `thenM_`
+
+ doptM Opt_WarnMissingFields `thenM` \ warn ->
+ checkM (not (warn && notNull missing_ns_fields))
+ (warnTc True (missingFields data_con missing_ns_fields))
+
where
- missing_strict_fields
+ missing_s_fields
= [ fl | (fl, str) <- field_info,
isMarkedStrict str,
not (fieldLabelName fl `elem` field_names_used)
]
- other_missing_fields
+ missing_ns_fields
= [ fl | (fl, str) <- field_info,
not (isMarkedStrict str),
not (fieldLabelName fl `elem` field_names_used)
]
- field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
+ field_names_used = recBindFields rbinds
field_labels = dataConFieldLabels data_con
field_info = zipEqual "missingFields"
field_labels
- (dropList ex_theta (dataConStrictMarks data_con))
- -- The 'drop' is because dataConStrictMarks
- -- includes the existential dictionaries
- (_, _, _, ex_theta, _, _) = dataConSig data_con
+ field_strs
+
+ 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], LIE)
+tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId]
-tcMonoExprs [] [] = returnTc ([], emptyLIE)
-tcMonoExprs (expr:exprs) (ty:tys)
- = tcMonoExpr expr ty `thenTc` \ (expr', lie1) ->
- tcMonoExprs exprs tys `thenTc` \ (exprs', lie2) ->
- returnTc (expr':exprs', lie1 `plusLIE` lie2)
+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, LIE)
-tcLit (HsLitLit s _) res_ty
- = tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass ->
- newDicts (LitLitOrigin (unpackFS s))
- [mkClassPred cCallableClass [res_ty]] `thenNF_Tc` \ dicts ->
- returnTc (HsLit (HsLitLit s res_ty), mkLIE dicts)
-
+tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId)
tcLit lit res_ty
- = unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_`
- returnTc (HsLit lit, emptyLIE)
+ = zapExpectedTo res_ty (hsLitType lit) `thenM_`
+ returnM (HsLit lit)
\end{code}
%* *
%************************************************************************
-Mini-utils:
-
Boring and alphabetical:
\begin{code}
arithSeqCtxt 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)
+
+fieldCtxt field_name
+ = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record")
+
+funAppCtxt fun arg arg_no
+ = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
+ quotes (ppr fun) <> text ", namely"])
+ 4 (quotes (ppr arg))
listCtxt expr
= hang (ptext SLIT("In the list element:")) 4 (ppr expr)
predCtxt expr
= hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-exprCtxt expr
- = hang (ptext SLIT("In the expression:")) 4 (ppr expr)
-
-funAppCtxt fun arg arg_no
- = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
- quotes (ppr fun) <> text ", namely"])
- 4 (quotes (ppr arg))
-
-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
-
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:"))
- 4 (pprQuotedList fields)
- where
- fields = [field | (field, _, _) <- rbinds]
+ 4 (pprQuotedList (recBindFields rbinds))
recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr
recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr
notSelector field
= hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
-missingStrictFieldCon :: Name -> FieldLabel -> SDoc
-missingStrictFieldCon con field
- = hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
- ptext SLIT("does not have the required strict field"), quotes (ppr field)]
+missingStrictFields :: DataCon -> [FieldLabel] -> SDoc
+missingStrictFields con fields
+ = header <> rest
+ where
+ rest | null fields = empty -- Happens for non-record constructors
+ -- with strict fields
+ | otherwise = colon <+> pprWithCommas ppr 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
+
+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 mkHsApp fun args -- Used in error messages
-missingFieldCon :: Name -> FieldLabel -> SDoc
-missingFieldCon con field
- = hsep [ptext SLIT("Field") <+> quotes (ppr field),
- ptext SLIT("is not initialised")]
+#ifdef GHCI
+polySpliceErr :: Id -> SDoc
+polySpliceErr id
+ = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
+#endif
\end{code}
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