\section[TcExpr]{Typecheck an expression}
\begin{code}
-module TcExpr ( tcExpr, tcPolyExpr, tcId ) where
+module TcExpr ( tcExpr, tcExpr_id, tcMonoExpr ) where
#include "HsVersions.h"
-import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
- HsBinds(..), Stmt(..), StmtCtxt(..),
- failureFreePat
+#ifdef GHCI /* Only if bootstrapped */
+import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
+import HsSyn ( HsReify(..), ReifyFlavour(..) )
+import TcType ( isTauTy )
+import TcEnv ( bracketOK, tcMetaTy, tcLookupGlobal,
+ wellStaged, metaLevel )
+import TcSimplify ( tcSimplifyBracket )
+import Name ( isExternalName )
+import qualified DsMeta
+#endif
+
+import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
+ mkMonoBind, recBindFields
)
import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds,
- mkHsTyApp
+import TcHsSyn ( TcExpr, TcRecordBinds, hsLitType, mkHsDictApp, mkHsTyApp, mkHsLet )
+import TcRnMonad
+import TcUnify ( tcSubExp, tcGen, (<$>),
+ unifyTauTy, unifyFunTy, unifyListTy, unifyPArrTy,
+ unifyTupleTy )
+import BasicTypes ( RecFlag(..), isMarkedStrict )
+import Inst ( InstOrigin(..),
+ newOverloadedLit, newMethodFromName, newIPDict,
+ newDicts, newMethodWithGivenTy,
+ instToId, tcInstCall, tcInstDataCon
)
-
-import TcMonad
-import BasicTypes ( RecFlag(..) )
-
-import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- LIE, emptyLIE, unitLIE, plusLIE, plusLIEs, newOverloadedLit,
- newMethod, newMethodWithGivenTy, newDicts, instToId )
import TcBinds ( tcBindsAndThen )
-import TcEnv ( tcInstId,
- tcLookupValue, tcLookupClassByKey,
- tcLookupValueByKey,
- tcExtendGlobalTyVars, tcLookupValueMaybe,
- tcLookupTyCon, tcLookupDataCon
+import TcEnv ( tcLookupClass, tcLookupGlobal_maybe, tcLookupIdLvl,
+ tcLookupTyCon, tcLookupDataCon, tcLookupId
)
-import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts )
-import TcMonoType ( tcHsType, checkSigTyVars, sigCtxt )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts )
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
import TcPat ( badFieldCon )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcTauType,
- tcInstTyVars,
- tcInstTcType, tcSplitRhoTy,
- newTyVarTy, newTyVarTy_OpenKind, zonkTcType )
-
-import Class ( Class )
-import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType )
-import Id ( idType, recordSelectorFieldLabel,
- isRecordSelector,
- Id
+import TcSimplify ( tcSimplifyIPs )
+import TcMType ( tcInstTyVars, tcInstType, newHoleTyVarTy, zapToType,
+ newTyVarTy, newTyVarTys, zonkTcType, readHoleResult )
+import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
+ tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
+ isSigmaTy, mkFunTy, mkFunTys,
+ mkTyConApp, mkClassPred, tcFunArgTy,
+ tyVarsOfTypes, isLinearPred,
+ liftedTypeKind, openTypeKind,
+ tcSplitSigmaTy, tcTyConAppTyCon,
+ tidyOpenType
)
-import DataCon ( dataConFieldLabels, dataConSig, dataConId )
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
+import Id ( Id, idType, recordSelectorFieldLabel, isRecordSelector, isDataConWrapId_maybe )
+import DataCon ( DataCon, dataConFieldLabels, dataConSig, dataConStrictMarks )
import Name ( Name )
-import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys,
- splitFunTy_maybe, splitFunTys,
- mkTyConApp,
- splitForAllTys, splitRhoTy,
- isTauTy, tyVarsOfType, tyVarsOfTypes,
- isForAllTy, splitAlgTyConApp, splitAlgTyConApp_maybe,
- boxedTypeKind, mkArrowKind,
- substTopTheta, tidyOpenType
- )
-import VarEnv ( zipVarEnv )
-import VarSet ( elemVarSet, mkVarSet )
-import TyCon ( tyConDataCons )
-import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy
- )
-import TysWiredIn ( boolTy, charTy, stringTy )
-import PrelInfo ( ioTyCon_NAME )
-import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy,
- unifyUnboxedTupleTy )
-import Unique ( cCallableClassKey, cReturnableClassKey,
- enumFromClassOpKey, enumFromThenClassOpKey,
- enumFromToClassOpKey, enumFromThenToClassOpKey,
- thenMClassOpKey, zeroClassOpKey, returnMClassOpKey
+import TyCon ( TyCon, tyConTyVars, tyConTheta, isAlgTyCon, tyConDataCons )
+import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import VarSet ( emptyVarSet, elemVarSet )
+import TysWiredIn ( boolTy )
+import PrelNames ( cCallableClassName, cReturnableClassName,
+ enumFromName, enumFromThenName,
+ enumFromToName, enumFromThenToName,
+ enumFromToPName, enumFromThenToPName,
+ ioTyConName
)
-import Outputable
-import Maybes ( maybeToBool )
import ListSetOps ( minusList )
+import CmdLineOpts
+import HscTypes ( TyThing(..) )
+
import Util
+import Outputable
+import FastString
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr :: RenamedHsExpr -- Expession to type check
- -> TcType -- Expected type (could be a polytpye)
- -> TcM s (TcExpr, LIE)
-
-tcExpr expr ty | isForAllTy ty = -- Polymorphic case
- tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) ->
- returnTc (expr', lie)
-
- | otherwise = -- Monomorphic case
- tcMonoExpr expr ty
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM TcExpr -- Generalised expr with expected type
+
+tcExpr expr expected_ty
+ = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
+ tc_expr' expr expected_ty
+
+tc_expr' expr expected_ty
+ | not (isSigmaTy expected_ty) -- Monomorphic case
+ = tcMonoExpr expr expected_ty
+
+ | otherwise
+ = tcGen expected_ty emptyVarSet (
+ tcMonoExpr expr
+ ) `thenM` \ (gen_fn, expr') ->
+ returnM (gen_fn <$> expr')
\end{code}
%************************************************************************
%* *
-\subsection{@tcPolyExpr@ typchecks an application}
-%* *
-%************************************************************************
-
-\begin{code}
--- tcPolyExpr is like tcMonoExpr, except that the expected type
--- can be a polymorphic one.
-tcPolyExpr :: RenamedHsExpr
- -> TcType -- Expected type
- -> TcM s (TcExpr, LIE, -- Generalised expr with expected type, and LIE
- TcExpr, TcTauType, LIE) -- Same thing, but instantiated; tau-type returned
-
-tcPolyExpr arg expected_arg_ty
- = -- Ha! The argument type of the function is a for-all type,
- -- An example of rank-2 polymorphism.
-
- -- To ensure that the forall'd type variables don't get unified with each
- -- other or any other types, we make fresh copy of the alleged type
- tcInstTcType expected_arg_ty `thenNF_Tc` \ (sig_tyvars, sig_rho) ->
- let
- (sig_theta, sig_tau) = splitRhoTy sig_rho
- in
- -- Type-check the arg and unify with expected type
- tcMonoExpr arg sig_tau `thenTc` \ (arg', lie_arg) ->
-
- -- Check that the sig_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.
-
- tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) $
- tcAddErrCtxtM (sigCtxt sig_msg expected_arg_ty) $
-
- checkSigTyVars sig_tyvars `thenTc` \ zonked_sig_tyvars ->
-
- newDicts SignatureOrigin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) ->
- -- ToDo: better origin
- tcSimplifyAndCheck
- (text "tcPolyExpr")
- (mkVarSet zonked_sig_tyvars)
- sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) ->
-
- let
- -- 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.
- generalised_arg = TyLam zonked_sig_tyvars $
- DictLam dict_ids $
- HsLet (MonoBind inst_binds [] Recursive)
- arg'
- in
- returnTc ( generalised_arg, free_insts,
- arg', sig_tau, lie_arg )
- where
- sig_msg ty = ptext SLIT("In an expression with expected type:") <+> ppr ty
-\end{code}
-
-%************************************************************************
-%* *
\subsection{The TAUT rules for variables}
%* *
%************************************************************************
\begin{code}
tcMonoExpr :: RenamedHsExpr -- Expession to type check
- -> TcTauType -- Expected type (could be a type variable)
- -> TcM s (TcExpr, LIE)
+ -> TcRhoType -- Expected type (could be a type variable)
+ -- Definitely no foralls at the top
+ -- Can be a 'hole'.
+ -> TcM TcExpr
tcMonoExpr (HsVar name) res_ty
- = tcId name `thenNF_Tc` \ (expr', lie, id_ty) ->
- unifyTauTy res_ty id_ty `thenTc_`
-
- -- 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 id_ty)
- (lurkingRank2Err name id_ty) `thenTc_`
-
- returnTc (expr', lie)
+ = tcId name `thenM` \ (expr', id_ty) ->
+ tcSubExp res_ty id_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> expr')
+
+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 `thenM` \ ip_ty ->
+ newIPDict (IPOcc 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}
+
%************************************************************************
%* *
-\subsection{Literals}
+\subsection{Expressions type signatures}
%* *
%************************************************************************
-Overloaded literals.
-
-\begin{code}
-tcMonoExpr (HsLit (HsInt i)) res_ty
- = newOverloadedLit (LiteralOrigin (HsInt i))
- (OverloadedIntegral i)
- res_ty `thenNF_Tc` \ stuff ->
- returnTc stuff
-
-tcMonoExpr (HsLit (HsFrac f)) res_ty
- = newOverloadedLit (LiteralOrigin (HsFrac f))
- (OverloadedFractional f)
- res_ty `thenNF_Tc` \ stuff ->
- returnTc stuff
-
-
-tcMonoExpr (HsLit lit@(HsLitLit s)) res_ty
- = tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- newDicts (LitLitOrigin (_UNPK_ s))
- [(cCallableClass, [res_ty])] `thenNF_Tc` \ (dicts, _) ->
- returnTc (HsLitOut lit res_ty, dicts)
-\end{code}
-
-Primitive literals:
-
\begin{code}
-tcMonoExpr (HsLit lit@(HsCharPrim c)) res_ty
- = unifyTauTy res_ty charPrimTy `thenTc_`
- returnTc (HsLitOut lit charPrimTy, emptyLIE)
-
-tcMonoExpr (HsLit lit@(HsStringPrim s)) res_ty
- = unifyTauTy res_ty addrPrimTy `thenTc_`
- returnTc (HsLitOut lit addrPrimTy, emptyLIE)
-
-tcMonoExpr (HsLit lit@(HsIntPrim i)) res_ty
- = unifyTauTy res_ty intPrimTy `thenTc_`
- returnTc (HsLitOut lit intPrimTy, emptyLIE)
-
-tcMonoExpr (HsLit lit@(HsFloatPrim f)) res_ty
- = unifyTauTy res_ty floatPrimTy `thenTc_`
- returnTc (HsLitOut lit floatPrimTy, emptyLIE)
-
-tcMonoExpr (HsLit lit@(HsDoublePrim d)) res_ty
- = unifyTauTy res_ty doublePrimTy `thenTc_`
- returnTc (HsLitOut lit doublePrimTy, emptyLIE)
+tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = addErrCtxt (exprSigCtxt in_expr) $
+ tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
+ tcExpr expr sig_tc_ty `thenM` \ expr' ->
+
+ -- Must instantiate the outer for-alls of sig_tc_ty
+ -- else we risk instantiating a ? res_ty to a forall-type
+ -- which breaks the invariant that tcMonoExpr only returns phi-types
+ tcInstCall SignatureOrigin sig_tc_ty `thenM` \ (inst_fn, inst_sig_ty) ->
+ tcSubExp res_ty inst_sig_ty `thenM` \ co_fn ->
+
+ returnM (co_fn <$> inst_fn expr')
+
+tcMonoExpr (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)
+ -- so it's not enabled yet.
+ -- Can't eliminate it altogether from the parser, because the
+ -- same parser parses *patterns*.
\end{code}
-Unoverloaded literals:
-
-\begin{code}
-tcMonoExpr (HsLit lit@(HsChar c)) res_ty
- = unifyTauTy res_ty charTy `thenTc_`
- returnTc (HsLitOut lit charTy, emptyLIE)
-
-tcMonoExpr (HsLit lit@(HsString str)) res_ty
- = unifyTauTy res_ty stringTy `thenTc_`
- returnTc (HsLitOut lit stringTy, emptyLIE)
-\end{code}
%************************************************************************
%* *
%************************************************************************
\begin{code}
-tcMonoExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go
- = tcMonoExpr expr res_ty
+tcMonoExpr (HsLit lit) res_ty = tcLit lit res_ty
+tcMonoExpr (HsOverLit lit) res_ty = newOverloadedLit (LiteralOrigin lit) lit res_ty
+tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsPar expr')
+tcMonoExpr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsSCC lbl expr')
--- perform the negate *before* overloading the integer, since the case
--- of minBound on Ints fails otherwise. Could be done elsewhere, but
--- convenient to do it here.
-tcMonoExpr (NegApp (HsLit (HsInt i)) neg) res_ty
- = tcMonoExpr (HsLit (HsInt (-i))) res_ty
-
-tcMonoExpr (NegApp expr neg) res_ty
- = tcMonoExpr (HsApp neg expr) res_ty
+tcMonoExpr (NegApp expr neg_name) res_ty
+ = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
+ -- ToDo: use tcSyntaxName
tcMonoExpr (HsLam match) res_ty
- = tcMatchLambda match res_ty `thenTc` \ (match',lie) ->
- returnTc (HsLam match', lie)
-
-tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2]
- where
- accum (HsApp e1 e2) args = accum e1 (e2:args)
- accum fun args
- = tcApp fun args res_ty `thenTc` \ (fun', args', lie) ->
- returnTc (foldl HsApp fun' args', lie)
+ = tcMatchLambda match res_ty `thenM` \ match' ->
+ returnM (HsLam match')
--- equivalent to (op e1) e2:
-tcMonoExpr (OpApp arg1 op fix arg2) res_ty
- = tcApp op [arg1,arg2] res_ty `thenTc` \ (op', [arg1', arg2'], lie) ->
- returnTc (OpApp arg1' op' fix arg2', lie)
+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
-tcMonoExpr in_expr@(SectionL arg op) res_ty
- = tcApp op [arg] res_ty `thenTc` \ (op', [arg'], lie) ->
-
- -- 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!
- tcAddErrCtxt (sectionLAppCtxt in_expr) $
- unifyFunTy res_ty `thenTc_`
-
- returnTc (SectionL arg' op', lie)
+tcMonoExpr in_expr@(SectionL arg1 op) res_ty
+ = tcExpr_id op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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 expr) res_ty
- = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
- tcAddErrCtxt (sectionRAppCtxt in_expr) $
- split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
- tcMonoExpr expr arg2_ty `thenTc` \ (expr',lie2) ->
- unifyTauTy res_ty (mkFunTy arg1_ty op_res_ty) `thenTc_`
- returnTc (SectionR op' expr', lie1 `plusLIE` lie2)
-\end{code}
+tcMonoExpr in_expr@(SectionR op arg2) res_ty
+ = tcExpr_id op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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')
-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 (CCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty
- = -- Get the callable and returnable classes.
- tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
- tcLookupClassByKey cReturnableClassKey `thenNF_Tc` \ cReturnableClass ->
- tcLookupTyCon ioTyCon_NAME `thenNF_Tc` \ ioTyCon ->
- let
- new_arg_dict (arg, arg_ty)
- = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
- [(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
- mapNF_Tc (\ _ -> newTyVarTy_OpenKind) [1..(length args)] `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 IO
- -- type constructor.
- newTyVarTy boxedTypeKind `thenNF_Tc` \ result_ty ->
- let
- io_result_ty = mkTyConApp ioTyCon [result_ty]
- [ioDataCon] = tyConDataCons ioTyCon
- 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 [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
+-- equivalent to (op e1) e2:
- returnTc (HsApp (HsVar (dataConId ioDataCon) `TyApp` [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)
+tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty
+ = tcExpr_id op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ 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}
\begin{code}
-tcMonoExpr (HsSCC label expr) res_ty
- = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
- returnTc (HsSCC label expr', lie)
-
tcMonoExpr (HsLet binds expr) res_ty
= tcBindsAndThen
combiner
binds -- Bindings to check
- tc_expr `thenTc` \ (expr', lie) ->
- returnTc (expr', lie)
+ (tcMonoExpr expr res_ty)
where
- tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
- returnTc (expr', lie)
- combiner is_rec bind expr = HsLet (MonoBind bind [] is_rec) expr
+ 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) $
+ = addSrcLoc src_loc $
+ addErrCtxt (caseCtxt in_expr) $
-- Typecheck the case alternatives first.
-- The case patterns tend to give good type info to use
-- 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 matches res_ty `thenM` \ (scrut_ty, matches') ->
- tcAddErrCtxt (caseScrutCtxt scrut) (
+ addErrCtxt (caseScrutCtxt scrut) (
tcMonoExpr scrut scrut_ty
- ) `thenTc` \ (scrut',lie1) ->
+ ) `thenM` \ scrut' ->
- returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
+ returnM (HsCase scrut' matches' src_loc)
tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
- = tcAddSrcLoc src_loc $
- tcAddErrCtxt (predCtxt pred) (
- tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
+ = addSrcLoc src_loc $
+ addErrCtxt (predCtxt pred) (
+ tcMonoExpr pred boolTy ) `thenM` \ pred' ->
+
+ zapToType res_ty `thenM` \ res_ty' ->
+ -- C.f. the call to zapToType in TcMatches.tcMatches
+
+ tcMonoExpr b1 res_ty' `thenM` \ b1' ->
+ tcMonoExpr b2 res_ty' `thenM` \ b2' ->
+ returnM (HsIf pred' b1' b2' src_loc)
+
+tcMonoExpr (HsDo do_or_lc stmts method_names _ src_loc) res_ty
+ = addSrcLoc src_loc $
+ tcDoStmts do_or_lc stmts method_names res_ty `thenM` \ (binds, stmts', methods') ->
+ returnM (mkHsLet binds (HsDo do_or_lc stmts' methods' res_ty src_loc))
+
+tcMonoExpr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
+ = unifyListTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitList elt_ty exprs')
+ where
+ tc_elt elt_ty expr
+ = addErrCtxt (listCtxt expr) $
+ tcMonoExpr expr elt_ty
- 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))
+tcMonoExpr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+ = unifyPArrTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitPArr elt_ty exprs')
+ where
+ tc_elt elt_ty expr
+ = addErrCtxt (parrCtxt expr) $
+ tcMonoExpr expr elt_ty
+
+tcMonoExpr (ExplicitTuple exprs boxity) res_ty
+ = unifyTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
+ tcMonoExprs exprs arg_tys `thenM` \ exprs' ->
+ returnM (ExplicitTuple exprs' boxity)
\end{code}
+
+%************************************************************************
+%* *
+ Foreign calls
+%* *
+%************************************************************************
+
+The interesting thing about @ccall@ is that it is just a template
+which we instantiate by filling in details about the types of its
+argument and result (ie minimal typechecking is performed). So, the
+basic story is that we allocate a load of type variables (to hold the
+arg/result types); unify them with the args/result; and store them for
+later use.
+
\begin{code}
-tcMonoExpr expr@(HsDo do_or_lc stmts src_loc) res_ty
- = tcDoStmts do_or_lc stmts src_loc res_ty
+tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty
+
+ = getDOpts `thenM` \ 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."])
+ `thenM_`
+
+ -- Get the callable and returnable classes.
+ tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
+ tcLookupClass cReturnableClassName `thenM` \ cReturnableClass ->
+ tcLookupTyCon ioTyConName `thenM` \ ioTyCon ->
+ let
+ new_arg_dict (arg, arg_ty)
+ = newDicts (CCallOrigin (unpackFS lbl) (Just arg))
+ [mkClassPred cCallableClass [arg_ty]] `thenM` \ arg_dicts ->
+ returnM arg_dicts -- Actually a singleton bag
+
+ result_origin = CCallOrigin (unpackFS lbl) Nothing {- Not an arg -}
+ in
+
+ -- Arguments
+ let tv_idxs | null args = []
+ | otherwise = [1..length args]
+ in
+ newTyVarTys (length tv_idxs) openTypeKind `thenM` \ arg_tys ->
+ tcMonoExprs args arg_tys `thenM` \ args' ->
+
+ -- The argument types can be unlifted or lifted; the result
+ -- type must, however, be lifted since it's an argument to the IO
+ -- type constructor.
+ newTyVarTy liftedTypeKind `thenM` \ result_ty ->
+ let
+ io_result_ty = mkTyConApp ioTyCon [result_ty]
+ in
+ unifyTauTy res_ty io_result_ty `thenM_`
+
+ -- Construct the extra insts, which encode the
+ -- constraints on the argument and result types.
+ mappM new_arg_dict (zipEqual "tcMonoExpr:CCall" args arg_tys) `thenM` \ ccarg_dicts_s ->
+ newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenM` \ ccres_dict ->
+ extendLIEs (ccres_dict ++ concat ccarg_dicts_s) `thenM_`
+ returnM (HsCCall lbl args' may_gc is_casm io_result_ty)
\end{code}
-\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 (ExplicitListOut elt_ty exprs', plusLIEs lies)
- where
- tc_elt elt_ty expr
- = tcAddErrCtxt (listCtxt expr) $
- tcMonoExpr expr elt_ty
-tcMonoExpr (ExplicitTuple exprs boxed) res_ty
- = (if boxed
- then unifyTupleTy (length exprs) res_ty
- else unifyUnboxedTupleTy (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' boxed, plusLIEs lies)
-
-tcMonoExpr (RecordCon con_name rbinds) res_ty
- = tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+%************************************************************************
+%* *
+ Record construction and update
+%* *
+%************************************************************************
+
+\begin{code}
+tcMonoExpr expr@(RecordCon con_name rbinds) res_ty
+ = addErrCtxt (recordConCtxt expr) $
+ tcId con_name `thenM` \ (con_expr, con_tau) ->
let
- (_, record_ty) = splitFunTys 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 (splitAlgTyConApp_maybe record_ty ) )
- unifyTauTy res_ty record_ty `thenTc_`
+ ASSERT( isAlgTyCon tycon )
+ unifyTauTy res_ty record_ty `thenM_`
-- Check that the record bindings match the constructor
- tcLookupDataCon con_name `thenTc` \ (data_con, _, _) ->
+ -- con_name is syntactically constrained to be a data constructor
+ tcLookupDataCon con_name `thenM` \ 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
+ if notNull bad_fields then
+ 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 record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
-
- returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie)
+ tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' ->
+
+ -- Check for missing fields
+ checkMissingFields data_con rbinds `thenM_`
+ returnM (RecordConOut data_con 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 (RecordUpd record_expr rbinds) res_ty
- = tcAddErrCtxt recordUpdCtxt $
+tcMonoExpr expr@(RecordUpd record_expr rbinds) res_ty
+ = addErrCtxt (recordUpdCtxt expr) $
- -- STEP 1
- -- Figure out the tycon and data cons from the first field name
- ASSERT( not (null rbinds) )
+ -- STEP 0
+ -- Check that the field names are really field names
+ ASSERT( notNull rbinds )
let
- ((first_field_name, _, _) : rest) = rbinds
+ field_names = recBindFields rbinds
+ in
+ mappM tcLookupGlobal_maybe field_names `thenM` \ maybe_sel_ids ->
+ 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
+ ]
in
- tcLookupValueMaybe first_field_name `thenNF_Tc` \ maybe_sel_id ->
- (case maybe_sel_id of
- Just sel_id | isRecordSelector sel_id -> returnTc sel_id
- other -> failWithTc (notSelector first_field_name)
- ) `thenTc` \ sel_id ->
+ 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
- (_, tau) = splitForAllTys (idType sel_id)
- Just (data_ty, _) = splitFunTy_maybe tau -- Must succeed since sel_id is a selector
- (tycon, _, data_cons) = splitAlgTyConApp data_ty
- (con_tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
+ -- 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
+ tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
in
- tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) ->
+ tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
-- STEP 2
- -- Check for bad fields
+ -- 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.
-- (Do this after checking for bad fields in case there's a field that
let
result_record_ty = mkTyConApp tycon result_inst_tys
in
- unifyTauTy res_ty result_record_ty `thenTc_`
- tcRecordBinds result_record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ unifyTauTy 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
- | otherwise = newTyVarTy boxedTypeKind -- Fresh 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 con_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) ->
+ tcMonoExpr record_expr record_ty `thenM` \ record_expr' ->
-- 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.
+ -- do pattern matching over the data cons.
--
- -- 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.
+ -- What dictionaries do we need?
+ -- We just take the context of the type constructor
let
- (tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
- inst_env = zipVarEnv tyvars result_inst_tys
- theta' = substTopTheta inst_env theta
+ theta' = substTheta inst_env (tyConTheta tycon)
in
- newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
+ newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
-- Phew!
- returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds',
- con_lie `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.. :]
+
+%* *
+%************************************************************************
+
+\begin{code}
tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
- = unifyListTy res_ty `thenTc` \ elt_ty ->
- tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) ->
+ = unifyListTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr elt_ty `thenM` \ expr' ->
- tcLookupValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- sel_id [elt_ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromName `thenM` \ enum_from ->
- returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'),
- lie1 `plusLIE` lie2)
+ returnM (ArithSeqOut (HsVar 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) ->
- tcLookupValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
-
- returnTc (ArithSeqOut (HsVar enum_from_then_id)
- (FromThen expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3)
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
+ tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenName `thenM` \ enum_from_then ->
+
+ returnM (ArithSeqOut (HsVar enum_from_then) (FromThen expr1' expr2'))
+
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) ->
- tcLookupValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
-
- returnTc (ArithSeqOut (HsVar enum_from_to_id)
- (FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3)
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
+ tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromToName `thenM` \ enum_from_to ->
+
+ returnM (ArithSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
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) ->
- tcLookupValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq)
- sel_id [elt_ty] `thenNF_Tc` \ (lie4, eft_id) ->
-
- returnTc (ArithSeqOut (HsVar eft_id)
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4)
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ unifyListTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
+ tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ tcMonoExpr expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenToName `thenM` \ eft ->
+
+ returnM (ArithSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+tcMonoExpr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ unifyPArrTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
+ tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromToPName `thenM` \ enum_from_to ->
+
+ returnM (PArrSeqOut (HsVar enum_from_to) (FromTo expr1' expr2'))
+
+tcMonoExpr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ unifyPArrTy res_ty `thenM` \ elt_ty ->
+ tcMonoExpr expr1 elt_ty `thenM` \ expr1' ->
+ tcMonoExpr expr2 elt_ty `thenM` \ expr2' ->
+ tcMonoExpr expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromThenToPName `thenM` \ eft ->
+
+ returnM (PArrSeqOut (HsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+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}
+ Template Haskell
%* *
%************************************************************************
\begin{code}
-tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = tcSetErrCtxt (exprSigCtxt in_expr) $
- tcHsType poly_ty `thenTc` \ sig_tc_ty ->
-
- if not (isForAllTy sig_tc_ty) then
- -- Easy case
- unifyTauTy sig_tc_ty res_ty `thenTc_`
- tcMonoExpr expr sig_tc_ty
-
- else -- Signature is polymorphic
- tcPolyExpr expr sig_tc_ty `thenTc` \ (_, _, expr, expr_ty, lie) ->
-
- -- Now match the signature type with res_ty.
- -- We must not do this earlier, because res_ty might well
- -- mention variables free in the environment, and we'd get
- -- bogus complaints about not being able to for-all the
- -- sig_tyvars
- unifyTauTy res_ty expr_ty `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 (inside tcPolyExpr), except for any default
- -- resolution it may have done, which is recorded in the
- -- substitution.
- returnTc (expr, lie)
+#ifdef GHCI /* Only if bootstrapped */
+ -- Rename excludes these cases otherwise
+
+tcMonoExpr (HsSplice n expr loc) res_ty = addSrcLoc loc (tcSpliceExpr n expr res_ty)
+
+tcMonoExpr (HsBracket brack loc) res_ty
+ = addSrcLoc loc $
+ getStage `thenM` \ level ->
+ case bracketOK level of {
+ Nothing -> failWithTc (illegalBracket level) ;
+ Just next_level ->
+
+ -- Typecheck expr to make sure it is valid,
+ -- but throw away the results. We'll type check
+ -- it again when we actually use it.
+ newMutVar [] `thenM` \ pending_splices ->
+ getLIEVar `thenM` \ lie_var ->
+
+ setStage (Brack next_level pending_splices lie_var) (
+ getLIE (tcBracket brack)
+ ) `thenM` \ (meta_ty, lie) ->
+ tcSimplifyBracket lie `thenM_`
+
+ unifyTauTy res_ty meta_ty `thenM_`
+
+ -- Return the original expression, not the type-decorated one
+ readMutVar pending_splices `thenM` \ pendings ->
+ returnM (HsBracketOut brack pendings)
+ }
+
+tcMonoExpr (HsReify (Reify flavour name)) res_ty
+ = addErrCtxt (ptext SLIT("At the reification of") <+> ppr name) $
+ tcMetaTy tycon_name `thenM` \ reify_ty ->
+ unifyTauTy res_ty reify_ty `thenM_`
+ returnM (HsReify (ReifyOut flavour name))
+ where
+ tycon_name = case flavour of
+ ReifyDecl -> DsMeta.decTyConName
+ ReifyType -> DsMeta.typTyConName
+ ReifyFixity -> pprPanic "tcMonoExpr: cant do reifyFixity yet" (ppr name)
+#endif GHCI
\end{code}
-Typecheck expression which in most cases will be an Id.
+%************************************************************************
+%* *
+\subsection{Implicit Parameter bindings}
+%* *
+%************************************************************************
\begin{code}
-tcExpr_id :: RenamedHsExpr
- -> TcM s (TcExpr,
- LIE,
- TcType)
-tcExpr_id id_expr
- = case id_expr of
- HsVar name -> tcId name `thenNF_Tc` \ stuff ->
- returnTc stuff
- other -> newTyVarTy_OpenKind `thenNF_Tc` \ id_ty ->
- tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
- returnTc (id_expr', lie_id, id_ty)
+tcMonoExpr (HsWith expr binds is_with) res_ty
+ = getLIE (tcMonoExpr expr res_ty) `thenM` \ (expr', expr_lie) ->
+ mapAndUnzipM tc_ip_bind binds `thenM` \ (avail_ips, binds') ->
+
+ -- If the binding binds ?x = E, we must now
+ -- discharge any ?x constraints in expr_lie
+ tcSimplifyIPs avail_ips expr_lie `thenM` \ dict_binds ->
+ let
+ expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr'
+ in
+ returnM (HsWith expr'' binds' is_with)
+ where
+ tc_ip_bind (ip, expr)
+ = newTyVarTy openTypeKind `thenM` \ ty ->
+ getSrcLocM `thenM` \ loc ->
+ newIPDict (IPBind ip) ip ty `thenM` \ (ip', ip_inst) ->
+ tcMonoExpr expr ty `thenM` \ expr' ->
+ returnM (ip_inst, (ip', expr'))
\end{code}
+
+%************************************************************************
+%* *
+ Catch-all
+%* *
+%************************************************************************
+
+\begin{code}
+tcMonoExpr 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 s (TcExpr, [TcExpr], -- Translated fun and args
- LIE)
+tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
+ -> TcType -- Expected result type of application
+ -> TcM TcExpr -- Translated fun and args
+
+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) ->
+ tcExpr_id fun `thenM` \ (fun', fun_ty) ->
- tcAddErrCtxt (wrongArgsCtxt "too many" fun args) (
+ 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) ->
-
- -- Unify with expected result before type-checking the args
- -- This is when we might detect a too-few args situation
- tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty) (
- unifyTauTy res_ty actual_result_ty
- ) `thenTc_`
+ ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
-- Now typecheck the args
- mapAndUnzipTc (tcArg fun)
- (zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) ->
+ mappM (tcArg fun)
+ (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
- -- 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 actual_result_ty)
- (lurkingRank2Err fun fun_ty) `thenTc_`
+ -- Unify with expected result after type-checking the args
+ -- so that the info from args percolates to actual_result_ty.
+ -- This is when we might detect a too-few args situation.
+ -- (One can think of cases when the opposite order would give
+ -- a better error message.)
+ addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
+ (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
- returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s)
+ returnM (co_fn <$> foldl HsApp 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' ->
+ = 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'
- (exp_args, _) = splitFunTys exp_ty''
- (act_args, _) = splitFunTys act_ty''
+ (exp_args, _) = tcSplitFunTys exp_ty''
+ (act_args, _) = tcSplitFunTys act_ty''
- message | length exp_args < length act_args = wrongArgsCtxt "too few" fun args
- | length exp_args > length act_args = wrongArgsCtxt "too many" fun args
- | otherwise = appCtxt fun args
+ len_act_args = length act_args
+ len_exp_args = length exp_args
+
+ 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)
+ returnM (env2, message)
split_fun_ty :: TcType -- The type of the function
- -> Int -- Number of arguments
- -> TcM s ([TcType], -- Function argument types
- TcType) -- Function result types
+ -> 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, TcType, Int) -- Actual argument and expected arg type
- -> TcM s (TcExpr, LIE) -- Resulting argument and LIE
+tcArg :: RenamedHsExpr -- The function (for error messages)
+ -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM TcExpr -- Resulting argument and LIE
tcArg the_fun (arg, expected_arg_ty, arg_no)
- = tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
+ = addErrCtxt (funAppCtxt the_fun arg arg_no) $
tcExpr arg expected_arg_ty
\end{code}
%* *
%************************************************************************
-\begin{code}
-tcId :: Name -> NF_TcM s (TcExpr, LIE, TcType)
+tcId instantiates an occurrence of an Id.
+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)}
+
+The -fno-method-sharing flag controls what happens so far as the LIE
+is concerned. The default case is that for an overloaded function we
+generate a "method" Id, and add the Method Inst to the LIE. So you get
+something like
+ f :: Num a => a -> a
+ f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x
+If you specify -fno-method-sharing, the dictionary application
+isn't shared, so we get
+ f :: Num a => a -> a
+ f = /\a (d:Num a) (x:a) -> (+) a d x x
+This gets a bit less sharing, but
+ a) it's better for RULEs involving overloaded functions
+ b) perhaps fewer separated lambdas
-tcId name
- = -- Look up the Id and instantiate its type
- tcLookupValueMaybe name `thenNF_Tc` \ maybe_local ->
+\begin{code}
+tcId :: Name -> TcM (TcExpr, TcType)
+tcId name -- Look up the Id and instantiate its type
+ = tcLookupIdLvl name `thenM` \ (id, bind_lvl) ->
+
+ -- Check for cross-stage lifting
+#ifdef GHCI
+ getStage `thenM` \ use_stage ->
+ case use_stage of
+ Brack use_lvl ps_var lie_var
+ | use_lvl > bind_lvl && not (isExternalName name)
+ -> -- E.g. \x -> [| h x |]
+ -- We must behave as if the reference to x was
+ -- h $(lift x)
+ -- We use 'x' itself as the splice proxy, used by
+ -- the desugarer to stitch it all back together
+ -- NB: isExernalName is true of top level things,
+ -- and false of nested bindings
+
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((name, HsApp (HsVar lift) (HsVar id)) : ps) `thenM_`
- case maybe_local of
- Just tc_id -> instantiate_it tc_id (idType tc_id)
+ returnM (HsVar id, id_ty))
- Nothing -> tcLookupValue name `thenNF_Tc` \ id ->
- tcInstId id `thenNF_Tc` \ (tyvars, theta, tau) ->
- instantiate_it2 id tyvars theta tau
+ other ->
+ let
+ use_lvl = metaLevel use_stage
+ in
+ checkTc (wellStaged bind_lvl use_lvl)
+ (badStageErr id bind_lvl use_lvl) `thenM_`
+#endif
+ -- This is the bit that handles the no-Template-Haskell case
+ case isDataConWrapId_maybe id of
+ Nothing -> loop (HsVar id) (idType id)
+ Just data_con -> inst_data_con id data_con
where
- -- 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) ->
- tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
- instantiate_it2 tc_id_occ tyvars theta tau
-
- instantiate_it2 tc_id_occ tyvars theta tau
- = if null theta then -- Is it overloaded?
- returnNF_Tc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau)
- else
- -- Yes, it's overloaded
- newMethodWithGivenTy (OccurrenceOf tc_id_occ)
- tc_id_occ arg_tys theta tau `thenNF_Tc` \ inst ->
- instantiate_it (instToId inst) tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
- returnNF_Tc (expr, unitLIE inst `plusLIE` lie2, final_tau)
-
- where
- arg_tys = mkTyVarTys tyvars
+ orig = OccurrenceOf name
+
+ loop (HsVar fun_id) fun_ty
+ | want_method_inst fun_ty
+ = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ newMethodWithGivenTy orig fun_id
+ (mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
+ loop (HsVar meth_id) tau
+
+ loop fun fun_ty
+ | isSigmaTy fun_ty
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
+ loop (inst_fn fun) tau
+
+ | otherwise
+ = 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.
+ -- 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:
+ -- let m = f %x in (m 3, m 4)
+ -- 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.
+
+ -- We treat data constructors differently, because we have to generate
+ -- constraints for their silly theta, which no longer appears in
+ -- the type of dataConWrapId. It's dual to TcPat.tcConstructor
+ inst_data_con id data_con
+ = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
+ extendLIEs ex_dicts `thenM_`
+ returnM (mkHsDictApp (mkHsTyApp (HsVar id) ty_args) (map instToId ex_dicts),
+ mkFunTys arg_tys result_ty)
\end{code}
-%************************************************************************
-%* *
-\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
-%* *
-%************************************************************************
+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}
-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 boxedTypeKind boxedTypeKind) `thenNF_Tc` \ m ->
- newTyVarTy boxedTypeKind `thenNF_Tc` \ elt_ty ->
- unifyTauTy res_ty (mkAppTy m elt_ty) `thenTc_`
-
- tcStmts do_or_lc (mkAppTy m) stmts elt_ty `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.
- --
- tcLookupValueByKey returnMClassOpKey `thenNF_Tc` \ return_sel_id ->
- tcLookupValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id ->
- tcLookupValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id ->
- newMethod DoOrigin return_sel_id [m] `thenNF_Tc` \ (return_lie, return_id) ->
- newMethod DoOrigin then_sel_id [m] `thenNF_Tc` \ (then_lie, then_id) ->
- newMethod DoOrigin zero_sel_id [m] `thenNF_Tc` \ (zero_lie, zero_id) ->
- let
- monad_lie = then_lie `plusLIE` return_lie `plusLIE` perhaps_zero_lie
- perhaps_zero_lie | all failure_free stmts' = emptyLIE
- | otherwise = zero_lie
-
- failure_free (BindStmt pat _ _) = failureFreePat pat
- failure_free (GuardStmt _ _) = False
- failure_free other_stmt = True
- in
- returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id res_ty src_loc,
- stmts_lie `plusLIE` monad_lie)
+tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, TcType)
+tcExpr_id (HsVar name) = tcId name
+tcExpr_id expr = newHoleTyVarTy `thenM` \ id_ty ->
+ tcMonoExpr expr id_ty `thenM` \ expr' ->
+ readHoleResult id_ty `thenM` \ id_ty' ->
+ returnM (expr', id_ty')
\end{code}
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 this type
+2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty.
-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.
+For each binding field = value
-4. Type check the value using tcArg, passing tau as the expected
- argument 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 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 -- Expected type of whole record
+ :: TyCon -- Type constructor for the record
+ -> [TcType] -- Args of this type constructor
-> RenamedRecordBinds
- -> TcM s (TcRecordBinds, LIE)
+ -> TcM TcRecordBinds
-tcRecordBinds expected_record_ty rbinds
- = mapAndUnzipTc do_bind rbinds `thenTc` \ (rbinds', lies) ->
- returnTc (rbinds', plusLIEs lies)
+tcRecordBinds tycon ty_args rbinds
+ = mappM do_bind rbinds
where
- do_bind (field_label, rhs, pun_flag)
- = tcLookupValue field_label `thenNF_Tc` \ sel_id ->
+ tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
+
+ do_bind (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)
+ in
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
- tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
+ tcExpr rhs field_ty `thenM` \ rhs' ->
- -- Record selectors all have type
- -- forall a1..an. T a1 .. an -> tau
- ASSERT( maybeToBool (splitFunTy_maybe tau) )
- let
- -- Selector must have type RecordType -> FieldType
- Just (record_ty, field_ty) = splitFunTy_maybe tau
- in
- unifyTauTy expected_record_ty record_ty `thenTc_`
- tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) ->
- returnTc ((sel_id, rhs', pun_flag), lie)
+ returnM (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)
+
+checkMissingFields :: DataCon -> RenamedRecordBinds -> 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_s_fields
+ = [ fl | (fl, str) <- field_info,
+ isMarkedStrict str,
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+ missing_ns_fields
+ = [ fl | (fl, str) <- field_info,
+ not (isMarkedStrict str),
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+
+ field_names_used = recBindFields rbinds
+ field_labels = dataConFieldLabels data_con
+
+ field_info = zipEqual "missingFields"
+ field_labels
+ field_strs
+
+ field_strs = dropList ex_theta (dataConStrictMarks data_con)
+ -- The 'drop' is because dataConStrictMarks
+ -- includes the existential dictionaries
+ (_, _, _, ex_theta, _, _) = dataConSig data_con
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM s ([TcExpr], LIE)
+tcMonoExprs :: [RenamedHsExpr] -> [TcType] -> TcM [TcExpr]
-tcMonoExprs [] [] = returnTc ([], emptyLIE)
+tcMonoExprs [] [] = returnM []
tcMonoExprs (expr:exprs) (ty:tys)
- = tcMonoExpr expr ty `thenTc` \ (expr', lie1) ->
- tcMonoExprs exprs tys `thenTc` \ (exprs', lie2) ->
- returnTc (expr':exprs', lie1 `plusLIE` lie2)
+ = tcMonoExpr expr ty `thenM` \ expr' ->
+ tcMonoExprs exprs tys `thenM` \ exprs' ->
+ returnM (expr':exprs')
\end{code}
-% =================================================
+%************************************************************************
+%* *
+\subsection{Literals}
+%* *
+%************************************************************************
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
+Overloaded literals.
-Mini-utils:
\begin{code}
-pp_nest_hang :: String -> SDoc -> SDoc
-pp_nest_hang label stuff = nest 2 (hang (text label) 4 stuff)
+tcLit :: HsLit -> TcType -> TcM TcExpr
+tcLit (HsLitLit s _) res_ty
+ = tcLookupClass cCallableClassName `thenM` \ cCallableClass ->
+ newDicts (LitLitOrigin (unpackFS s))
+ [mkClassPred cCallableClass [res_ty]] `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
+ returnM (HsLit (HsLitLit s res_ty))
+
+tcLit lit res_ty
+ = unifyTauTy res_ty (hsLitType lit) `thenM_`
+ returnM (HsLit lit)
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
Boring and alphabetical:
\begin{code}
arithSeqCtxt expr
= hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
+
+badStageErr id bind_lvl use_lvl
+ = ptext SLIT("Stage error:") <+> quotes (ppr id) <+>
+ hsep [ptext SLIT("is bound at stage") <+> ppr bind_lvl,
+ ptext SLIT("but used at stage") <+> ppr use_lvl]
+
+parrSeqCtxt expr
+ = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
+
caseCtxt expr
= hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
= hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
exprSigCtxt expr
- = hang (ptext SLIT("In an expression with a type signature:"))
+ = hang (ptext SLIT("When checking the type signature of the expression:"))
4 (ppr expr)
-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)
-sectionRAppCtxt expr
- = hang (ptext SLIT("In the right section:")) 4 (ppr expr)
-
-sectionLAppCtxt expr
- = hang (ptext SLIT("In the left section:")) 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))
-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
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
+
+parrCtxt expr
+ = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr)
+
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
+
+illegalBracket level
+ = ptext SLIT("Illegal bracket at level") <+> ppr level
appCtxt fun args
- = ptext SLIT("In the application") <+> (ppr the_app)
+ = 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")])
-
-rank2ArgCtxt arg expected_arg_ty
- = ptext SLIT("In a polymorphic function argument:") <+> ppr arg
+ ptext SLIT("so that the result type has for-alls in it:") <+> ppr fun_ty])
badFieldsUpd rbinds
= hang (ptext SLIT("No constructor has all these fields:"))
- 4 (pprQuotedList fields)
- where
- fields = [field | (field, _, _) <- rbinds]
+ 4 (pprQuotedList (recBindFields rbinds))
-recordUpdCtxt = ptext SLIT("In a record update construct")
+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")]
+
+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
+
+polySpliceErr :: Id -> SDoc
+polySpliceErr id
+ = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
+
+wrongArgsCtxt too_many_or_few fun args
+ = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun)
+ <+> ptext SLIT("is applied to") <+> text too_many_or_few
+ <+> ptext SLIT("arguments in the call"))
+ 4 (parens (ppr the_app))
+ where
+ the_app = foldl HsApp fun args -- Used in error messages
\end{code}
projects / ghc-hetmet.git / blobdiff