%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcExpr]{Typecheck an expression}
\begin{code}
-#include "HsVersions.h"
-
-module TcExpr ( tcExpr, tcId ) where
+module TcExpr ( tcExpr, tcMonoExpr, tcId ) where
-IMP_Ubiq()
+#include "HsVersions.h"
-import HsSyn ( HsExpr(..), Qualifier(..), Stmt(..),
- HsBinds(..), Bind(..), MonoBinds(..),
- ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds,
- Match, Fake, InPat, OutPat, HsType, Fixity,
- pprParendExpr, failureFreePat, collectPatBinders )
-import RnHsSyn ( SYN_IE(RenamedHsExpr), SYN_IE(RenamedQual),
- SYN_IE(RenamedStmt), SYN_IE(RenamedRecordBinds)
- )
-import TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcQual), SYN_IE(TcStmt),
- TcIdOcc(..), SYN_IE(TcRecordBinds),
- mkHsTyApp
+import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
+ HsMatchContext(..), HsDoContext(..), mkMonoBind
)
+import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
+import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy )
import TcMonad
-import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- SYN_IE(LIE), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
- newMethod, newMethodWithGivenTy, newDicts )
-import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
- tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars,
- tcExtendGlobalTyVars
+import TcUnify ( tcSub, tcGen, (<$>),
+ unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy,
+ unifyTupleTy )
+import BasicTypes ( RecFlag(..), isMarkedStrict )
+import Inst ( InstOrigin(..),
+ LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs,
+ newOverloadedLit, newMethod, newIPDict,
+ newDicts,
+ instToId, tcInstId
)
-import SpecEnv ( SpecEnv )
-import TcMatches ( tcMatchesCase, tcMatch )
-import TcMonoType ( tcHsType )
-import TcPat ( tcPat )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( SYN_IE(TcType), TcMaybe(..),
- tcInstId, tcInstType, tcInstSigTcType,
- tcInstSigType, tcInstTcType, tcInstTheta,
- newTyVarTy, zonkTcTyVars, zonkTcType )
-import TcKind ( TcKind )
-
-import Class ( SYN_IE(Class), classSig )
-import FieldLabel ( fieldLabelName )
-import Id ( idType, dataConFieldLabels, dataConSig, SYN_IE(Id), GenId )
-import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
-import GenSpecEtc ( checkSigTyVars )
-import Name ( Name{-instance Eq-} )
-import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy,
- getTyVar_maybe, getFunTy_maybe, instantiateTy,
- splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy,
- isTauTy, mkFunTys, tyVarsOfType, getForAllTy_maybe,
- getAppDataTyCon, maybeAppDataTyCon
+import TcBinds ( tcBindsAndThen )
+import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe,
+ tcLookupTyCon, tcLookupDataCon, tcLookupId
)
-import TyVar ( GenTyVar, SYN_IE(TyVarSet), unionTyVarSets, mkTyVarSet )
-import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy, realWorldTy
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
+import TcPat ( badFieldCon )
+import TcSimplify ( tcSimplifyIPs )
+import TcMType ( tcInstTyVars, newTyVarTy, newTyVarTys, zonkTcType )
+import TcType ( TcType, TcSigmaType, TcPhiType,
+ tcSplitFunTys, tcSplitTyConApp,
+ isSigmaTy, mkFunTy, mkAppTy, mkTyConTy,
+ mkTyConApp, mkClassPred, tcFunArgTy,
+ tyVarsOfTypes,
+ liftedTypeKind, openTypeKind, mkArrowKind,
+ tcSplitSigmaTy, tcTyConAppTyCon,
+ tidyOpenType
)
-import TysWiredIn ( addrTy,
- boolTy, charTy, stringTy, mkListTy,
- mkTupleTy, mkPrimIoTy, stDataCon
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( dataConFieldLabels, dataConSig,
+ dataConStrictMarks
)
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
- enumFromClassOpKey, enumFromThenClassOpKey,
- enumFromToClassOpKey, enumFromThenToClassOpKey,
- thenMClassOpKey, zeroClassOpKey
+import Name ( Name )
+import TyCon ( TyCon, tyConTyVars, isAlgTyCon, tyConDataCons )
+import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import VarSet ( elemVarSet )
+import TysWiredIn ( boolTy, mkListTy, mkPArrTy, listTyCon, parrTyCon )
+import PrelNames ( cCallableClassName,
+ cReturnableClassName,
+ enumFromName, enumFromThenName,
+ enumFromToName, enumFromThenToName,
+ enumFromToPName, enumFromThenToPName,
+ thenMName, failMName, returnMName, ioTyConName
)
-import Outputable ( interpp'SP )
-import PprType ( GenType, GenTyVar ) -- Instances
-import Maybes ( maybeToBool )
-import Pretty
+import Outputable
+import ListSetOps ( minusList )
import Util
-\end{code}
+import CmdLineOpts
+import HscTypes ( TyThing(..) )
-\begin{code}
-tcExpr :: RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType s)
\end{code}
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{Main wrappers}
%* *
%************************************************************************
\begin{code}
-tcExpr (HsVar name)
- = tcId name `thenNF_Tc` \ (expr', lie, res_ty) ->
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM (TcExpr, LIE) -- Generalised expr with expected type, and LIE
- -- Check that the result type doesn't have any nested for-alls.
- -- For example, a "build" on its own is no good; it must be
- -- applied to something.
- checkTc (isTauTy res_ty)
- (lurkingRank2Err name res_ty) `thenTc_`
+tcExpr expr expected_ty
+ | not (isSigmaTy expected_ty) -- Monomorphic case
+ = tcMonoExpr expr expected_ty
- returnTc (expr', lie, res_ty)
+ | otherwise
+ = tcGen expected_ty (tcMonoExpr expr) `thenTc` \ (gen_fn, expr', lie) ->
+ returnTc (gen_fn <$> expr', lie)
\end{code}
+
%************************************************************************
%* *
-\subsection{Literals}
+\subsection{The TAUT rules for variables}
%* *
%************************************************************************
-Overloaded literals.
-
\begin{code}
-tcExpr (HsLit (HsInt i))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
-
- newOverloadedLit (LiteralOrigin (HsInt i))
- (OverloadedIntegral i)
- ty `thenNF_Tc` \ (lie, over_lit_id) ->
-
- returnTc (HsVar over_lit_id, lie, ty)
-
-tcExpr (HsLit (HsFrac f))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
-
- newOverloadedLit (LiteralOrigin (HsFrac f))
- (OverloadedFractional f)
- ty `thenNF_Tc` \ (lie, over_lit_id) ->
-
- returnTc (HsVar over_lit_id, lie, ty)
-
-tcExpr (HsLit lit@(HsLitLit s))
- = tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ ty ->
- newDicts (LitLitOrigin (_UNPK_ s))
- [(cCallableClass, ty)] `thenNF_Tc` \ (dicts, _) ->
- returnTc (HsLitOut lit ty, dicts, ty)
+tcMonoExpr :: RenamedHsExpr -- Expession to type check
+ -> TcPhiType -- Expected type (could be a type variable)
+ -- Definitely no foralls at the top
+ -- Can be a 'hole'.
+ -> TcM (TcExpr, LIE)
+
+tcMonoExpr (HsVar name) res_ty
+ = tcId name `thenNF_Tc` \ (expr', lie1, id_ty) ->
+ tcSub res_ty id_ty `thenTc` \ (co_fn, lie2) ->
+ returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
+
+tcMonoExpr (HsIPVar ip) res_ty
+ = -- Implicit parameters must have a *tau-type* not a
+ -- type scheme. We enforce this by creating a fresh
+ -- type variable as its type. (Because res_ty may not
+ -- be a tau-type.)
+ newTyVarTy openTypeKind `thenNF_Tc` \ ip_ty ->
+ newIPDict (IPOcc ip) ip ip_ty `thenNF_Tc` \ (ip', inst) ->
+ tcSub res_ty ip_ty `thenTc` \ (co_fn, lie) ->
+ returnNF_Tc (co_fn <$> HsIPVar ip', lie `plusLIE` unitLIE inst)
\end{code}
-Primitive literals:
-\begin{code}
-tcExpr (HsLit lit@(HsCharPrim c))
- = returnTc (HsLitOut lit charPrimTy, emptyLIE, charPrimTy)
-
-tcExpr (HsLit lit@(HsStringPrim s))
- = returnTc (HsLitOut lit addrPrimTy, emptyLIE, addrPrimTy)
-
-tcExpr (HsLit lit@(HsIntPrim i))
- = returnTc (HsLitOut lit intPrimTy, emptyLIE, intPrimTy)
-
-tcExpr (HsLit lit@(HsFloatPrim f))
- = returnTc (HsLitOut lit floatPrimTy, emptyLIE, floatPrimTy)
-
-tcExpr (HsLit lit@(HsDoublePrim d))
- = returnTc (HsLitOut lit doublePrimTy, emptyLIE, doublePrimTy)
-\end{code}
-
-Unoverloaded literals:
+%************************************************************************
+%* *
+\subsection{Expressions type signatures}
+%* *
+%************************************************************************
\begin{code}
-tcExpr (HsLit lit@(HsChar c))
- = returnTc (HsLitOut lit charTy, emptyLIE, charTy)
-
-tcExpr (HsLit lit@(HsString str))
- = returnTc (HsLitOut lit stringTy, emptyLIE, stringTy)
+tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = tcHsSigType ExprSigCtxt poly_ty `thenTc` \ sig_tc_ty ->
+ tcAddErrCtxt (exprSigCtxt in_expr) $
+ tcExpr expr sig_tc_ty `thenTc` \ (expr', lie1) ->
+ tcSub res_ty sig_tc_ty `thenTc` \ (co_fn, lie2) ->
+ returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
\end{code}
+
%************************************************************************
%* *
\subsection{Other expression forms}
%************************************************************************
\begin{code}
-tcExpr (HsPar expr) -- preserve parens so printing needn't guess where they go
- = tcExpr expr
-
-tcExpr (NegApp expr neg) = tcExpr (HsApp neg expr)
+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
-tcExpr (HsLam match)
- = tcMatch match `thenTc` \ (match',lie,ty) ->
- returnTc (HsLam match', lie, ty)
+tcMonoExpr (NegApp expr neg_name) res_ty
+ = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
-tcExpr (HsApp e1 e2) = accum e1 [e2]
- where
- accum (HsApp e1 e2) args = accum e1 (e2:args)
- accum fun args
- = tcApp fun args `thenTc` \ (fun', args', lie, res_ty) ->
- returnTc (foldl HsApp fun' args', lie, res_ty)
+tcMonoExpr (HsLam match) res_ty
+ = tcMatchLambda match res_ty `thenTc` \ (match',lie) ->
+ returnTc (HsLam match', lie)
--- equivalent to (op e1) e2:
-tcExpr (OpApp arg1 op fix arg2)
- = tcApp op [arg1,arg2] `thenTc` \ (op', [arg1', arg2'], lie, res_ty) ->
- returnTc (OpApp arg1' op' fix arg2', lie, res_ty)
+tcMonoExpr (HsApp e1 e2) res_ty
+ = tcApp e1 [e2] res_ty
\end{code}
Note that the operators in sections are expected to be binary, and
-- or just
-- op e
-tcExpr in_expr@(SectionL arg op)
- = tcApp op [arg] `thenTc` \ (op', [arg'], lie, res_ty) ->
-
- -- Check that res_ty is a function type
- -- Without this check we barf in the desugarer on
- -- f op = (3 `op`)
- -- because it tries to desugar to
- -- f op = \r -> 3 op r
- -- so (3 `op`) had better be a function!
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
- tcAddErrCtxt (sectionLAppCtxt in_expr) $
- unifyTauTy (mkFunTy ty1 ty2) res_ty `thenTc_`
-
- returnTc (SectionL arg' op', lie, res_ty)
+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) $
+ tcSub res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ returnTc (co_fn <$> SectionL arg1' op', lie1 `plusLIE` lie2 `plusLIE` lie3)
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcExpr in_expr@(SectionR op expr)
- = tcExpr op `thenTc` \ (op', lie1, op_ty) ->
- tcExpr expr `thenTc` \ (expr',lie2, expr_ty) ->
+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) $
+ tcSub res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ returnTc (co_fn <$> SectionR op' arg2', lie1 `plusLIE` lie2 `plusLIE` lie3)
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
- tcAddErrCtxt (sectionRAppCtxt in_expr) $
- unifyTauTy (mkFunTys [ty1, expr_ty] ty2) op_ty `thenTc_`
+-- equivalent to (op e1) e2:
- returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2)
+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) $
+ tcSub res_ty op_res_ty `thenTc` \ (co_fn, lie3) ->
+ returnTc (OpApp arg1' op' fix arg2',
+ lie1 `plusLIE` lie2a `plusLIE` lie2b `plusLIE` lie3)
\end{code}
The interesting thing about @ccall@ is that it is just a template
later use.
\begin{code}
-tcExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty)
- = -- Get the callable and returnable classes.
- tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass ->
+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 (_UNPK_ lbl) (Just arg))
- [(cCallableClass, arg_ty)] `thenNF_Tc` \ (arg_dicts, _) ->
+ [mkClassPred cCallableClass [arg_ty]] `thenNF_Tc` \ arg_dicts ->
returnNF_Tc arg_dicts -- Actually a singleton bag
result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -}
in
-- Arguments
- tcExprs args `thenTc` \ (args', args_lie, arg_tys) ->
+ 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 unboxed or boxed; the result
- -- type must, however, be boxed since it's an argument to the PrimIO
+ -- 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 mkBoxedTypeKind `thenNF_Tc` \ result_ty ->
+ 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 "tcExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) ->
-
- returnTc (HsApp (HsVar (RealId stDataCon) `TyApp` [realWorldTy, result_ty])
- (CCall lbl args' may_gc is_asm result_ty),
- -- do the wrapping in the newtype constructor here
- foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie,
- mkPrimIoTy result_ty)
+ 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}
-tcExpr (HsSCC label expr)
- = tcExpr expr `thenTc` \ (expr', lie, expr_ty) ->
- -- No unification. Give SCC the type of expr
- returnTc (HsSCC label expr', lie, expr_ty)
+tcMonoExpr (HsSCC lbl expr) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (HsSCC lbl expr', lie)
-tcExpr (HsLet binds expr)
+tcMonoExpr (HsLet binds expr) res_ty
= tcBindsAndThen
- HsLet -- The combiner
+ combiner
binds -- Bindings to check
- (tcExpr expr) -- Typechecker for the expression
-
-tcExpr in_expr@(HsCase expr matches src_loc)
- = tcAddSrcLoc src_loc $
- tcExpr expr `thenTc` \ (expr',lie1,expr_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ result_ty ->
-
- tcAddErrCtxt (caseCtxt in_expr) $
- tcMatchesCase (mkFunTy expr_ty result_ty) matches
- `thenTc` \ (matches',lie2) ->
-
- returnTc (HsCase expr' matches' src_loc, plusLIE lie1 lie2, result_ty)
-
-tcExpr (HsIf pred b1 b2 src_loc)
+ tc_expr `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
+ where
+ tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
+ returnTc (expr', lie)
+ combiner is_rec bind expr = HsLet (mkMonoBind bind [] is_rec) expr
+
+tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
+ = tcAddSrcLoc src_loc $
+ tcAddErrCtxt (caseCtxt in_expr) $
+
+ -- 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 `thenTc` \ (scrut_ty, matches', lie2) ->
+
+ tcAddErrCtxt (caseScrutCtxt scrut) (
+ tcMonoExpr scrut scrut_ty
+ ) `thenTc` \ (scrut',lie1) ->
+
+ returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
+
+tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
= tcAddSrcLoc src_loc $
- tcExpr pred `thenTc` \ (pred',lie1,predTy) ->
-
tcAddErrCtxt (predCtxt pred) (
- unifyTauTy boolTy predTy
- ) `thenTc_`
-
- tcExpr b1 `thenTc` \ (b1',lie2,result_ty) ->
- tcExpr b2 `thenTc` \ (b2',lie3,b2Ty) ->
-
- tcAddErrCtxt (branchCtxt b1 b2) $
- unifyTauTy result_ty b2Ty `thenTc_`
+ tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
- returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty)
-
-tcExpr (ListComp expr quals)
- = tcListComp expr quals `thenTc` \ ((expr',quals'), lie, ty) ->
- returnTc (ListComp expr' quals', lie, ty)
+ 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}
\begin{code}
-tcExpr expr@(HsDo stmts src_loc)
- = tcDoStmts stmts src_loc
+tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty
+ = tcDoStmts do_or_lc stmts src_loc res_ty
\end{code}
\begin{code}
-tcExpr (ExplicitList [])
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty)
-
-
-tcExpr in_expr@(ExplicitList exprs) -- Non-empty list
- = tcExprs exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) ->
- tcAddErrCtxt (listCtxt in_expr) $
- unifyTauTyList tys `thenTc_`
- returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty)
-
-tcExpr (ExplicitTuple exprs)
- = tcExprs exprs `thenTc` \ (exprs', lie, tys) ->
- returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys)
-
-tcExpr (RecordCon (HsVar con) rbinds)
- = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+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)
+ where
+ tc_elt elt_ty expr
+ = tcAddErrCtxt (listCtxt expr) $
+ tcMonoExpr 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)
+ 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) ->
let
- (_, record_ty) = splitFunTy con_tau
+ (_, record_ty) = tcSplitFunTys con_tau
+ (tycon, ty_args) = tcSplitTyConApp record_ty
in
- -- Con is syntactically constrained to be a data constructor
- ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) )
-
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ ASSERT( isAlgTyCon tycon )
+ unifyTauTy res_ty record_ty `thenTc_`
-- Check that the record bindings match the constructor
- tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
- checkTc (checkRecordFields rbinds con_id)
- (badFieldsCon con rbinds) `thenTc_`
-
- returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty)
-
--- One small complication in RecordUpd is that we have to generate some
--- dictionaries for the data type context, since we are going to
--- do some construction.
+ -- con_name is syntactically constrained to be a data constructor
+ tcLookupDataCon con_name `thenTc` \ data_con ->
+ let
+ bad_fields = badFields rbinds data_con
+ in
+ if not (null bad_fields) then
+ mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_`
+ failTc -- Fail now, because tcRecordBinds will crash on a bad field
+ else
+
+ -- Typecheck the record bindings
+ tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+
+ 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 && not (null missing_fields)))
+ (mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_`
+ returnNF_Tc ()) `thenNF_Tc_`
+
+ returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie)
+
+-- The main complication with RecordUpd is that we need to explicitly
+-- handle the *non-updated* fields. Consider:
--
--- What dictionaries do we need? For the moment we assume that all
--- data constructors have the same context, and grab it from the first
--- constructor. If they have varying contexts then we'd have to
--- union the ones that could participate in the update.
-
-tcExpr (RecordUpd record_expr rbinds)
- = ASSERT( not (null rbinds) )
- tcAddErrCtxt recordUpdCtxt $
+-- data T a b = MkT1 { fa :: a, fb :: b }
+-- | MkT2 { fa :: a, fc :: Int -> Int }
+-- | MkT3 { fd :: a }
+--
+-- upd :: T a b -> c -> T a c
+-- upd t x = t { fb = x}
+--
+-- The type signature on upd is correct (i.e. the result should not be (T a b))
+-- because upd should be equivalent to:
+--
+-- upd t x = case t of
+-- MkT1 p q -> MkT1 p x
+-- MkT2 a b -> MkT2 p b
+-- MkT3 d -> error ...
+--
+-- So we need to give a completely fresh type to the result record,
+-- and then constrain it by the fields that are *not* updated ("p" above).
+--
+-- Note that because MkT3 doesn't contain all the fields being updated,
+-- its RHS is simply an error, so it doesn't impose any type constraints
+--
+-- All this is done in STEP 4 below.
- tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty
+ = tcAddErrCtxt (recordUpdCtxt expr) $
- -- Check that the field names are plausible
- zonkTcType record_ty `thenNF_Tc` \ record_ty' ->
+ -- STEP 0
+ -- Check that the field names are really field names
+ ASSERT( not (null rbinds) )
+ let
+ field_names = [field_name | (field_name, _, _) <- rbinds]
+ in
+ mapNF_Tc tcLookupGlobal_maybe field_names `thenNF_Tc` \ maybe_sel_ids ->
let
- (tycon, inst_tys, data_cons) = --trace "TcExpr.getAppDataTyCon" $
- getAppDataTyCon record_ty'
- -- The record binds are non-empty (syntax); so at least one field
- -- label will have been unified with record_ty by tcRecordBinds;
- -- field labels must be of data type; hencd the getAppDataTyCon must succeed.
- (tyvars, theta, _, _) = dataConSig (head data_cons)
+ 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
+ ]
in
- tcInstTheta (zipEqual "tcExpr:RecordUpd" tyvars inst_tys) theta `thenNF_Tc` \ theta' ->
- newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
- checkTc (any (checkRecordFields rbinds) data_cons)
- (badFieldsUpd rbinds) `thenTc_`
-
- returnTc (RecordUpdOut record_expr' dicts rbinds',
- con_lie `plusLIE` record_lie `plusLIE` rbinds_lie,
- record_ty)
-
-tcExpr (ArithSeqIn seq@(From expr))
- = tcExpr expr `thenTc` \ (expr', lie1, ty) ->
+ checkTcM (null bad_guys) (listNF_Tc bad_guys `thenNF_Tc_` failTc) `thenTc_`
+
+ -- 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
+ data_cons = tyConDataCons tycon
+ (con_tyvars, _, _, _, _, _) = dataConSig (head data_cons)
+ in
+ tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) ->
- tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
+ -- 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_`
- returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'),
- lie1 `plusLIE` lie2,
- mkListTy ty)
+ -- STEP 3
+ -- Typecheck the update bindings.
+ -- (Do this after checking for bad fields in case there's a field that
+ -- doesn't match the constructor.)
+ 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) ->
+
+ -- STEP 4
+ -- Use the un-updated fields to find a vector of booleans saying
+ -- which type arguments must be the same in updatee and result.
+ --
+ -- 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']
+ con_field_lbls_s = map dataConFieldLabels data_cons
-tcExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
+ -- A constructor is only relevant to this process if
+ -- it contains all the fields that are being updated
+ relevant_field_lbls_s = filter is_relevant con_field_lbls_s
+ is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1, ty2] `thenTc_`
+ non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
+ common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
- tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
+ mk_inst_ty (tyvar, result_inst_ty)
+ | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
+ | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+ in
+ mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
- returnTc (ArithSeqOut (HsVar enum_from_then_id)
- (FromThen expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3,
- mkListTy ty1)
+ -- 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) ->
+
+ -- STEP 6
+ -- Figure out the LIE we need. We have to generate some
+ -- dictionaries for the data type context, since we are going to
+ -- do some construction.
+ --
+ -- What dictionaries do we need? For the moment we assume that all
+ -- data constructors have the same context, and grab it from the first
+ -- constructor. If they have varying contexts then we'd have to
+ -- union the ones that could participate in the update.
+ let
+ (tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
+ inst_env = mkTopTyVarSubst tyvars result_inst_tys
+ theta' = substTheta inst_env theta
+ in
+ newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts ->
-tcExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
+ -- Phew!
+ returnTc (RecordUpdOut record_expr' record_ty result_record_ty (map instToId dicts) rbinds',
+ mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie)
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1,ty2] `thenTc_`
+tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
+ = unifyListTy res_ty `thenTc` \ elt_ty ->
+ tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) ->
- tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
+ tcLookupGlobalId enumFromName `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
-
- returnTc (ArithSeqOut (HsVar enum_from_to_id)
+ sel_id [elt_ty] `thenNF_Tc` \ enum_from ->
+
+ returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'),
+ lie1 `plusLIE` unitLIE enum_from)
+
+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) ->
+ tcLookupGlobalId enumFromThenName `thenNF_Tc` \ sel_id ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_then ->
+
+ 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) ->
+ tcLookupGlobalId enumFromToName `thenNF_Tc` \ sel_id ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_to ->
+
+ returnTc (ArithSeqOut (HsVar (instToId enum_from_to))
(FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3,
- mkListTy ty1)
-
-tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3))
- = tcExpr expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr expr2 `thenTc` \ (expr2',lie2,ty2) ->
- tcExpr expr3 `thenTc` \ (expr3',lie3,ty3) ->
-
- tcAddErrCtxt (arithSeqCtxt in_expr) $
- unifyTauTyList [ty1,ty2,ty3] `thenTc_`
-
- tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- (RealId sel_id) [ty1] `thenNF_Tc` \ (lie4, eft_id) ->
-
- returnTc (ArithSeqOut (HsVar eft_id)
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4,
- mkListTy ty1)
+ 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) ->
+ tcLookupGlobalId enumFromThenToName `thenNF_Tc` \ sel_id ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft ->
+
+ returnTc (ArithSeqOut (HsVar (instToId eft))
+ (FromThenTo expr1' expr2' expr3'),
+ lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft)
+
+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) ->
+ tcLookupGlobalId enumFromToPName `thenNF_Tc` \ sel_id ->
+ newMethod (PArrSeqOrigin seq) sel_id [elt_ty] `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) ->
+ tcLookupGlobalId enumFromThenToPName `thenNF_Tc` \ sel_id ->
+ newMethod (PArrSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft ->
+
+ returnTc (PArrSeqOut (HsVar (instToId eft))
+ (FromThenTo expr1' expr2' expr3'),
+ lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft)
+
+tcMonoExpr (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{Expressions type signatures}
+\subsection{Implicit Parameter bindings}
%* *
%************************************************************************
\begin{code}
-tcExpr in_expr@(ExprWithTySig expr poly_ty)
- = tcExpr expr `thenTc` \ (texpr, lie, tau_ty) ->
- tcHsType poly_ty `thenTc` \ sigma_sig ->
-
- -- Check the tau-type part
- tcSetErrCtxt (exprSigCtxt in_expr) $
- tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' ->
- let
- (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
- in
- unifyTauTy sig_tau' tau_ty `thenTc_`
-
- -- Check the type variables of the signature
- checkSigTyVars sig_tyvars' sig_tau' `thenTc_`
-
- -- Check overloading constraints
- newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) ->
- tcSimplifyAndCheck
- (mkTyVarSet sig_tyvars')
- sig_dicts lie `thenTc_`
-
- -- If everything is ok, return the stuff unchanged, except for
- -- the effect of any substutions etc. We simply discard the
- -- result of the tcSimplifyAndCheck, except for any default
- -- resolution it may have done, which is recorded in the
- -- substitution.
- returnTc (texpr, lie, tau_ty)
+tcMonoExpr (HsWith expr binds) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) ->
+ mapAndUnzip3Tc tcIPBind binds `thenTc` \ (avail_ips, binds', bind_lies) ->
+
+ -- 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', 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)
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
- -> TcM s (TcExpr s, [TcExpr s], -- Translated fun and args
- LIE s,
- TcType s) -- Type of the application
-
-tcApp fun args
- = -- First type-check the function
- -- In the HsVar case we go straight to tcId to avoid hitting the
- -- rank-2 check, which we check later here anyway
- (case fun of
- HsVar name -> tcId name `thenNF_Tc` \ stuff -> returnTc stuff
- other -> tcExpr fun
- ) `thenTc` \ (fun', lie_fun, fun_ty) ->
-
- tcApp_help fun 1 fun_ty args `thenTc` \ (args', lie_args, res_ty) ->
- -- Check that the result type doesn't have any nested for-alls.
- -- For example, a "build" on its own is no good; it must be applied to something.
- checkTc (isTauTy res_ty)
- (lurkingRank2Err fun fun_ty) `thenTc_`
+tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
+ -> TcType -- Expected result type of application
+ -> TcM (TcExpr, LIE) -- Translated fun and args
- returnTc (fun', args', lie_fun `plusLIE` lie_args, res_ty)
+tcApp (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) ->
+
+ tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
+ 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) ->
+
+ -- 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.)
+ tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
+ (tcSub res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) ->
+
+ returnTc (co_fn <$> foldl HsApp fun' args',
+ lie_res `plusLIE` lie_fun `plusLIE` plusLIEs lie_args_s)
+
+
+-- 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' ->
+ let
+ (env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
+ (env2, act_ty'') = tidyOpenType env1 act_ty'
+ (exp_args, _) = tcSplitFunTys exp_ty''
+ (act_args, _) = tcSplitFunTys act_ty''
-tcApp_help :: RenamedHsExpr -> Int -- Function and arg position, used in error message(s)
- -> TcType s -- The type of the function
- -> [RenamedHsExpr] -- Arguments
- -> TcM s ([TcExpr s], -- Typechecked args
- LIE s,
- TcType s) -- Result type of the application
-
-tcApp_help orig_fun arg_no fun_ty []
- = returnTc ([], emptyLIE, fun_ty)
+ len_act_args = length act_args
+ len_exp_args = length exp_args
-tcApp_help orig_fun arg_no fun_ty all_args@(arg:args)
- = -- Expect the function to have type A->B
- tcAddErrCtxt (tooManyArgsCtxt orig_fun) (
- unifyFunTy fun_ty
- ) `thenTc` \ (expected_arg_ty, result_ty) ->
+ message | len_exp_args < len_act_args = wrongArgsCtxt "too few" fun args
+ | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args
+ | otherwise = appCtxt fun args
+ in
+ returnNF_Tc (env2, message)
- -- Type check the argument
- tcAddErrCtxt (funAppCtxt orig_fun arg_no arg) (
- tcArg expected_arg_ty arg
- ) `thenTc` \ (arg', lie_arg) ->
- -- Do the other args
- tcApp_help orig_fun (arg_no+1) result_ty args `thenTc` \ (args', lie_args, res_ty) ->
+split_fun_ty :: TcType -- The type of the function
+ -> Int -- Number of arguments
+ -> TcM ([TcType], -- Function argument types
+ TcType) -- Function result types
- -- Done
- returnTc (arg':args', lie_arg `plusLIE` lie_args, res_ty)
+split_fun_ty fun_ty 0
+ = returnTc ([], 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)
\end{code}
\begin{code}
-tcArg :: TcType s -- Expected arg type
- -> RenamedHsExpr -- Actual argument
- -> TcM s (TcExpr s, LIE s) -- Resulting argument and LIE
-
-tcArg expected_arg_ty arg
- | not (maybeToBool (getForAllTy_maybe expected_arg_ty))
- = -- The ordinary, non-rank-2 polymorphic case
- tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy expected_arg_ty actual_arg_ty `thenTc_`
- returnTc (arg', lie_arg)
+tcArg :: RenamedHsExpr -- The function (for error messages)
+ -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (TcExpr, LIE) -- Resulting argument and LIE
- | otherwise
- = -- Ha! The argument type of the function is a for-all type,
- -- An example of rank-2 polymorphism.
-
- -- No need to instantiate the argument type... it's must be the result
- -- of instantiating a function involving rank-2 polymorphism, so there
- -- isn't any danger of using the same tyvars twice
- -- The argument type shouldn't be overloaded type (hence ASSERT)
-
- -- To ensure that the forall'd type variables don't get unified with each
- -- other or any other types, we make fresh *signature* type variables
- -- and unify them with the tyvars.
- tcInstSigTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) ->
- let
- (sig_theta, sig_tau) = splitRhoTy sig_rho
- in
- ASSERT( null sig_theta ) -- And expected_tyvars are all DontBind things
-
- -- Type-check the arg and unify with expected type
- tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy sig_tau actual_arg_ty `thenTc_`
-
- -- Check that the arg_tyvars havn't been constrained
- -- The interesting bit here is that we must include the free variables
- -- of the expected arg ty. Here's an example:
- -- runST (newVar True)
- -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool))
- -- for (newVar True), with s fresh. Then we unify with the runST's arg type
- -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool.
- -- So now s' isn't unconstrained because it's linked to a.
- -- Conclusion: include the free vars of the expected arg type in the
- -- list of "free vars" for the signature check.
-
- tcAddErrCtxt (rank2ArgCtxt arg expected_arg_ty) (
- tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) (
- checkSigTyVars sig_tyvars sig_tau
- ) `thenTc_`
-
- -- Check that there's no overloading involved
- -- Even if there isn't, there may be some Insts which mention the expected_tyvars,
- -- but which, on simplification, don't actually need a dictionary involving
- -- the tyvar. So we have to do a proper simplification right here.
- tcSimplifyRank2 (mkTyVarSet sig_tyvars)
- lie_arg `thenTc` \ (free_insts, inst_binds) ->
-
- -- This HsLet binds any Insts which came out of the simplification.
- -- It's a bit out of place here, but using AbsBind involves inventing
- -- a couple of new names which seems worse.
- returnTc (TyLam sig_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts)
- )
- where
-
- mk_binds [] = EmptyBinds
- mk_binds ((inst,rhs):inst_binds)
- = (SingleBind (NonRecBind (VarMonoBind inst rhs))) `ThenBinds`
- mk_binds inst_binds
+tcArg the_fun (arg, expected_arg_ty, arg_no)
+ = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
+ tcExpr arg expected_arg_ty
\end{code}
+
%************************************************************************
%* *
\subsection{@tcId@ typchecks an identifier occurrence}
%************************************************************************
\begin{code}
-tcId :: Name -> NF_TcM s (TcExpr s, LIE s, TcType s)
-
-tcId name
- = -- Look up the Id and instantiate its type
- tcLookupLocalValue name `thenNF_Tc` \ maybe_local ->
-
- case maybe_local of
- Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id)
-
- Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
- tcInstType [] (idType id) `thenNF_Tc` \ inst_ty ->
- let
- (tyvars, rho) = splitForAllTy inst_ty
- in
- instantiate_it2 (RealId id) tyvars rho
-
- where
- -- The instantiate_it loop runs round instantiating the Id.
- -- It has to be a loop because we are now prepared to entertain
- -- types like
- -- f:: forall a. Eq a => forall b. Baz b => tau
- -- We want to instantiate this to
- -- f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
- instantiate_it tc_id_occ ty
- = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) ->
- instantiate_it2 tc_id_occ tyvars rho
-
- instantiate_it2 tc_id_occ tyvars rho
- | null theta -- Is it overloaded?
- = returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau)
-
- | otherwise -- Yes, it's overloaded
- = newMethodWithGivenTy (OccurrenceOf tc_id_occ)
- tc_id_occ arg_tys rho `thenNF_Tc` \ (lie1, meth_id) ->
- instantiate_it meth_id tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
- returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
-
- where
- (theta, tau) = splitRhoTy rho
- arg_tys = mkTyVarTys tyvars
+tcId :: Name -> NF_TcM (TcExpr, LIE, TcType)
+tcId name -- Look up the Id and instantiate its type
+ = tcLookupId name `thenNF_Tc` \ id ->
+ tcInstId id
\end{code}
-%************************************************************************
-%* *
-\subsection{@tcQuals@ typechecks list-comprehension qualifiers}
-%* *
-%************************************************************************
+Typecheck expression which in most cases will be an Id.
\begin{code}
-tcListComp expr []
- = tcExpr expr `thenTc` \ (expr', lie, ty) ->
- returnTc ((expr',[]), lie, mkListTy ty)
-
-tcListComp expr (qual@(FilterQual filter) : quals)
- = tcAddErrCtxt (qualCtxt qual) (
- tcExpr filter `thenTc` \ (filter', filter_lie, filter_ty) ->
- unifyTauTy boolTy filter_ty `thenTc_`
- returnTc (FilterQual filter', filter_lie)
- ) `thenTc` \ (qual', qual_lie) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), rest_lie, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- qual_lie `plusLIE` rest_lie,
- res_ty)
-
-tcListComp expr (qual@(GeneratorQual pat rhs) : quals)
- = newMonoIds binder_names mkBoxedTypeKind (\ ids ->
-
- tcAddErrCtxt (qualCtxt qual) (
- tcPat pat `thenTc` \ (pat', lie_pat, pat_ty) ->
- tcExpr rhs `thenTc` \ (rhs', lie_rhs, rhs_ty) ->
- -- NB: the environment has been extended with the new binders
- -- which the rhs can't "see", but the renamer should have made
- -- sure that everything is distinct by now, so there's no problem.
- -- Putting the tcExpr before the newMonoIds messes up the nesting
- -- of error contexts, so I didn't bother
-
- unifyTauTy (mkListTy pat_ty) rhs_ty `thenTc_`
- returnTc (GeneratorQual pat' rhs',
- lie_pat `plusLIE` lie_rhs)
- ) `thenTc` \ (qual', lie_qual) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), lie_rest, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- lie_qual `plusLIE` lie_rest,
- res_ty)
- )
- where
- binder_names = collectPatBinders pat
-
-tcListComp expr (LetQual binds : quals)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (tcListComp expr quals)
- where
- combine binds' (expr',quals') = (expr', LetQual binds' : quals')
+tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, LIE, TcType)
+tcExpr_id (HsVar name) = tcId name
+tcExpr_id expr = newTyVarTy openTypeKind `thenNF_Tc` \ id_ty ->
+ tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) ->
+ returnTc (expr', lie_id, id_ty)
\end{code}
%************************************************************************
\begin{code}
-tcDoStmts stmts src_loc
+-- I don't like this lumping together of do expression and list/array
+-- comprehensions; creating the monad instances is entirely pointless in the
+-- latter case; I'll leave the list case as it is for the moment, but handle
+-- arrays extra (would be better to handle arrays and lists together, though)
+-- -=chak
+--
+tcDoStmts PArrComp stmts src_loc res_ty
+ =
+ ASSERT( not (null stmts) )
+ tcAddSrcLoc src_loc $
+
+ unifyPArrTy res_ty `thenTc` \elt_ty ->
+ let tc_ty = mkTyConTy parrTyCon
+ m_ty = (mkPArrTy, elt_ty)
+ in
+ tcStmts (DoCtxt PArrComp) m_ty stmts `thenTc` \(stmts', stmts_lie) ->
+ returnTc (HsDoOut PArrComp stmts'
+ undefined undefined undefined -- don't touch!
+ res_ty src_loc,
+ stmts_lie)
+
+tcDoStmts do_or_lc stmts src_loc res_ty
= -- get the Monad and MonadZero classes
-- create type consisting of a fresh monad tyvar
+ ASSERT( not (null stmts) )
tcAddSrcLoc src_loc $
- newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m ->
+ -- If it's a comprehension we're dealing with,
+ -- force it to be a list comprehension.
+ -- (as of Haskell 98, monad comprehensions are no more.)
+ -- Similarily, array comprehensions must involve parallel arrays types
+ -- -=chak
+ (case do_or_lc of
+ ListComp -> unifyListTy res_ty `thenTc` \ elt_ty ->
+ returnNF_Tc (mkTyConTy listTyCon, (mkListTy, elt_ty))
- -- Build the then and zero methods in case we need them
- tcLookupGlobalValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id ->
- tcLookupGlobalValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id ->
- newMethod DoOrigin
- (RealId then_sel_id) [m] `thenNF_Tc` \ (m_lie, then_id) ->
- newMethod DoOrigin
- (RealId zero_sel_id) [m] `thenNF_Tc` \ (mz_lie, zero_id) ->
+ PArrComp -> panic "TcExpr.tcDoStmts: How did we get here?!?"
+
+ _ -> newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m_ty ->
+ newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty ->
+ unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenTc_`
+ returnNF_Tc (m_ty, (mkAppTy m_ty, elt_ty))
+ ) `thenNF_Tc` \ (tc_ty, m_ty) ->
+ tcStmts (DoCtxt do_or_lc) m_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.
+ --
+ tcLookupGlobalId returnMName `thenNF_Tc` \ return_sel_id ->
+ tcLookupGlobalId thenMName `thenNF_Tc` \ then_sel_id ->
+ tcLookupGlobalId failMName `thenNF_Tc` \ fail_sel_id ->
+ newMethod DoOrigin return_sel_id [tc_ty] `thenNF_Tc` \ return_inst ->
+ newMethod DoOrigin then_sel_id [tc_ty] `thenNF_Tc` \ then_inst ->
+ newMethod DoOrigin fail_sel_id [tc_ty] `thenNF_Tc` \ fail_inst ->
let
- get_m_arg ty
- = newTyVarTy mkTypeKind `thenNF_Tc` \ arg_ty ->
- unifyTauTy (mkAppTy m arg_ty) ty `thenTc_`
- returnTc arg_ty
-
- go [stmt@(ExprStmt exp src_loc)]
- = tcAddSrcLoc src_loc $
- tcSetErrCtxt (stmtCtxt stmt) $
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- returnTc ([ExprStmt exp' src_loc], exp_lie, exp_ty)
-
- go (stmt@(ExprStmt exp src_loc) : stmts)
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- get_m_arg exp_ty `thenTc` \ a ->
- returnTc (a, exp', exp_lie)
- )) `thenTc` \ (a, exp', exp_lie) ->
- go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) ->
- get_m_arg stmts_ty `thenTc` \ b ->
- returnTc (ExprStmtOut exp' src_loc a b : stmts',
- exp_lie `plusLIE` stmts_lie `plusLIE` m_lie,
- stmts_ty)
-
- go (stmt@(BindStmt pat exp src_loc) : stmts)
- = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) ->
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- -- See comments with tcListComp on GeneratorQual
-
- get_m_arg exp_ty `thenTc` \ a ->
- unifyTauTy pat_ty a `thenTc_`
- returnTc (a, pat', exp', pat_lie `plusLIE` exp_lie)
- )) `thenTc` \ (a, pat', exp', stmt_lie) ->
- go stmts `thenTc` \ (stmts', stmts_lie, stmts_ty) ->
- get_m_arg stmts_ty `thenTc` \ b ->
- returnTc (BindStmtOut pat' exp' src_loc a b : stmts',
- stmt_lie `plusLIE` stmts_lie `plusLIE` m_lie `plusLIE`
- (if failureFreePat pat' then emptyLIE else mz_lie),
- stmts_ty)
-
- go (LetStmt binds : stmts)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (go stmts)
- where
- combine binds' stmts' = LetStmt binds' : stmts'
+ monad_lie = mkLIE [return_inst, then_inst, fail_inst]
in
-
- go stmts `thenTc` \ (stmts', final_lie, final_ty) ->
- returnTc (HsDoOut stmts' then_id zero_id src_loc,
- final_lie,
- final_ty)
+ returnTc (HsDoOut do_or_lc stmts'
+ (instToId return_inst) (instToId then_inst) (instToId fail_inst)
+ res_ty src_loc,
+ stmts_lie `plusLIE` monad_lie)
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Record bindings}
+%* *
+%************************************************************************
+
Game plan for record bindings
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-For each binding
- field = value
-1. look up "field", to find its selector Id, which must have type
- forall a1..an. T a1 .. an -> tau
- where tau is the type of the field.
+1. Find the TyCon for the bindings, from the first field label.
+
+2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty.
-2. Instantiate this type
+For each binding field = value
-3. Unify the (T a1 .. an) part with the "expected result type", which
- is passed in. This checks that all the field labels come from the
- same type.
+3. Instantiate the field type (from the field label) using the type
+ envt from step 2.
-4. Type check the value using tcArg, passing tau as the expected
- argument type.
+4 Type check the value using tcArg, passing the field type as
+ the expected argument type.
This extends OK when the field types are universally quantified.
-Actually, to save excessive creation of fresh type variables,
-we
\begin{code}
tcRecordBinds
- :: TcType s -- Expected type of whole record
+ :: TyCon -- Type constructor for the record
+ -> [TcType] -- Args of this type constructor
-> RenamedRecordBinds
- -> TcM s (TcRecordBinds s, LIE s)
+ -> TcM (TcRecordBinds, LIE)
-tcRecordBinds expected_record_ty rbinds
+tcRecordBinds tycon ty_args rbinds
= mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) ->
returnTc (rbinds', plusLIEs lies)
where
- do_bind (field_label, rhs, pun_flag)
- = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
- tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
+ tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
- -- Record selectors all have type
- -- forall a1..an. T a1 .. an -> tau
- ASSERT( maybeToBool (getFunTy_maybe tau) )
+ do_bind (field_lbl_name, rhs, pun_flag)
+ = tcLookupGlobalId field_lbl_name `thenNF_Tc` \ sel_id ->
let
- -- Selector must have type RecordType -> FieldType
- Just (record_ty, field_ty) = getFunTy_maybe tau
+ field_lbl = recordSelectorFieldLabel sel_id
+ field_ty = substTy tenv (fieldLabelType field_lbl)
in
- unifyTauTy expected_record_ty record_ty `thenTc_`
- tcArg field_ty rhs `thenTc` \ (rhs', lie) ->
- returnTc ((RealId sel_id, rhs', pun_flag), lie)
-
-checkRecordFields :: RenamedRecordBinds -> Id -> Bool -- True iff all the fields in
- -- RecordBinds are field of the
- -- specified constructor
-checkRecordFields rbinds data_con
- = all ok rbinds
- where
- data_con_fields = dataConFieldLabels data_con
-
- ok (field_name, _, _) = any (match (getName field_name)) data_con_fields
+ ASSERT( isRecordSelector sel_id )
+ -- 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 `thenTc` \ (rhs', lie) ->
+
+ returnTc ((sel_id, rhs', pun_flag), lie)
+
+badFields rbinds data_con
+ = [field_name | (field_name, _, _) <- rbinds,
+ not (field_name `elem` field_names)
+ ]
+ where
+ field_names = map fieldLabelName (dataConFieldLabels data_con)
- match field_name field_label = field_name == fieldLabelName field_label
+missingFields rbinds data_con
+ | null field_labels = ([], []) -- Not declared as a record;
+ -- But C{} is still valid
+ | otherwise
+ = (missing_strict_fields, other_missing_fields)
+ where
+ missing_strict_fields
+ = [ fl | (fl, str) <- field_info,
+ isMarkedStrict str,
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+ other_missing_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_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
\end{code}
%************************************************************************
%* *
-\subsection{@tcExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions}
%* *
%************************************************************************
\begin{code}
-tcExprs :: [RenamedHsExpr] -> TcM s ([TcExpr s], LIE s, [TcType s])
+tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM ([TcExpr], LIE)
-tcExprs [] = returnTc ([], emptyLIE, [])
-tcExprs (expr:exprs)
- = tcExpr expr `thenTc` \ (expr', lie1, ty) ->
- tcExprs exprs `thenTc` \ (exprs', lie2, tys) ->
- returnTc (expr':exprs', lie1 `plusLIE` lie2, ty:tys)
+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)
\end{code}
-% =================================================
+%************************************************************************
+%* *
+\subsection{Literals}
+%* *
+%************************************************************************
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
+Overloaded literals.
-Mini-utils:
\begin{code}
-pp_nest_hang :: String -> Pretty -> Pretty
-pp_nest_hang label stuff = ppNest 2 (ppHang (ppStr label) 4 stuff)
+tcLit :: HsLit -> TcType -> TcM (TcExpr, LIE)
+tcLit (HsLitLit s _) res_ty
+ = tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass ->
+ newDicts (LitLitOrigin (_UNPK_ s))
+ [mkClassPred cCallableClass [res_ty]] `thenNF_Tc` \ dicts ->
+ returnTc (HsLit (HsLitLit s res_ty), mkLIE dicts)
+
+tcLit lit res_ty
+ = unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_`
+ returnTc (HsLit lit, emptyLIE)
\end{code}
-Boring and alphabetical:
-\begin{code}
-arithSeqCtxt expr sty
- = ppHang (ppStr "In an arithmetic sequence:") 4 (ppr sty expr)
-branchCtxt b1 b2 sty
- = ppSep [ppStr "In the branches of a conditional:",
- pp_nest_hang "`then' branch:" (ppr sty b1),
- pp_nest_hang "`else' branch:" (ppr sty b2)]
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
-caseCtxt expr sty
- = ppHang (ppStr "In a case expression:") 4 (ppr sty expr)
+Mini-utils:
-exprSigCtxt expr sty
- = ppHang (ppStr "In an expression with a type signature:")
- 4 (ppr sty expr)
+Boring and alphabetical:
+\begin{code}
+arithSeqCtxt expr
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
-listCtxt expr sty
- = ppHang (ppStr "In a list expression:") 4 (ppr sty expr)
+parrSeqCtxt expr
+ = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
-predCtxt expr sty
- = ppHang (ppStr "In a predicate expression:") 4 (ppr sty expr)
+caseCtxt expr
+ = hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
-sectionRAppCtxt expr sty
- = ppHang (ppStr "In a right section:") 4 (ppr sty expr)
+caseScrutCtxt expr
+ = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
-sectionLAppCtxt expr sty
- = ppHang (ppStr "In a left section:") 4 (ppr sty expr)
+exprSigCtxt expr
+ = hang (ptext SLIT("In an expression with a type signature:"))
+ 4 (ppr expr)
-funAppCtxt fun arg_no arg sty
- = ppHang (ppCat [ ppStr "In the", speakNth arg_no, ppStr "argument of",
- ppr sty fun `ppBeside` ppStr ", namely"])
- 4 (pprParendExpr sty arg)
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
-qualCtxt qual sty
- = ppHang (ppStr "In a list-comprehension qualifer:")
- 4 (ppr sty qual)
+parrCtxt expr
+ = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr)
-stmtCtxt stmt sty
- = ppHang (ppStr "In a do statement:")
- 4 (ppr sty stmt)
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
-tooManyArgsCtxt f sty
- = ppHang (ppStr "Too many arguments in an application of the function")
- 4 (ppr sty f)
+exprCtxt expr
+ = hang (ptext SLIT("In the expression:")) 4 (ppr expr)
-lurkingRank2Err fun fun_ty sty
- = ppHang (ppCat [ppStr "Illegal use of", ppr sty fun])
- 4 (ppAboves [ppStr "It is applied to too few arguments,",
- ppStr "so that the result type has for-alls in it"])
+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))
-rank2ArgCtxt arg expected_arg_ty sty
- = ppHang (ppStr "In a polymorphic function argument:")
- 4 (ppSep [ppBeside (ppr sty arg) (ppStr " ::"),
- ppr sty expected_arg_ty])
+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
-badFieldsUpd rbinds sty
- = ppHang (ppStr "No constructor has all these fields:")
- 4 (interpp'SP sty fields)
+appCtxt fun args
+ = ptext SLIT("In the application") <+> quotes (ppr the_app)
where
- fields = [field | (field, _, _) <- rbinds]
+ the_app = foldl HsApp fun args -- Used in error messages
-recordUpdCtxt sty = ppStr "In a record update construct"
+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])
-badFieldsCon con rbinds sty
- = ppHang (ppBesides [ppStr "Inconsistent constructor:", ppr sty con])
- 4 (ppBesides [ppStr "and fields:", interpp'SP sty fields])
+badFieldsUpd rbinds
+ = hang (ptext SLIT("No constructor has all these fields:"))
+ 4 (pprQuotedList fields)
where
fields = [field | (field, _, _) <- 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)]
+
+missingFieldCon :: Name -> FieldLabel -> SDoc
+missingFieldCon con field
+ = hsep [ptext SLIT("Field") <+> quotes (ppr field),
+ ptext SLIT("is not initialised")]
\end{code}
projects / ghc-hetmet.git / blobdiff