%
-% (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}
-module TcExpr ( tcExpr, tcStmt, tcId ) where
+module TcExpr ( tcExpr, tcPolyExpr, tcId ) where
#include "HsVersions.h"
import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
- HsBinds(..), Stmt(..), DoOrListComp(..),
- failureFreePat, collectPatBinders
+ HsBinds(..), Stmt(..), StmtCtxt(..),
+ failureFreePat
)
-import RnHsSyn ( RenamedHsExpr,
- RenamedStmt, RenamedRecordBinds
- )
-import TcHsSyn ( TcExpr, TcStmt,
- TcRecordBinds,
+import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
+import TcHsSyn ( TcExpr, TcRecordBinds,
mkHsTyApp
)
import BasicTypes ( RecFlag(..) )
import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- LIE, emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
- newMethod, newMethodWithGivenTy, newDicts )
-import TcBinds ( tcBindsAndThen, checkSigTyVars )
-import TcEnv ( TcIdOcc(..), tcInstId,
+ LIE, emptyLIE, unitLIE, plusLIE, plusLIEs, newOverloadedLit,
+ newMethod, newMethodWithGivenTy, newDicts, instToId )
+import TcBinds ( tcBindsAndThen )
+import TcEnv ( TcIdOcc(..), tcInstId, tidyType,
tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
- tcLookupGlobalValueByKey, newMonoIds,
+ tcLookupGlobalValueByKey,
tcExtendGlobalTyVars, tcLookupGlobalValueMaybe,
- tcLookupTyCon
+ tcLookupTyCon, tcLookupDataCon
)
import TcMatches ( tcMatchesCase, tcMatchExpected )
-import TcMonoType ( tcHsType )
-import TcPat ( tcPat )
+import TcGRHSs ( tcStmts )
+import TcMonoType ( tcHsTcType, checkSigTyVars, sigCtxt )
+import TcPat ( badFieldCon )
import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcMaybe(..),
- tcInstType, tcInstSigTcType, tcInstTyVars,
- tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy,
- newTyVarTy, newTyVarTys, zonkTcType )
-import TcKind ( TcKind )
+import TcType ( TcType, TcTauType, TcMaybe(..),
+ tcInstTyVars,
+ tcInstTcType, tcSplitRhoTy,
+ newTyVarTy, zonkTcType )
import Class ( Class )
import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType )
-import Id ( idType, dataConFieldLabels, dataConSig, recordSelectorFieldLabel,
+import Id ( idType, recordSelectorFieldLabel,
isRecordSelector,
- Id, GenId
+ Id
)
-import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
-import Name ( Name{-instance Eq-} )
+import DataCon ( dataConFieldLabels, dataConSig, dataConId )
+import Name ( Name )
import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys,
splitFunTy_maybe, splitFunTys,
mkTyConApp,
- splitForAllTys, splitRhoTy, splitSigmaTy,
+ splitForAllTys, splitRhoTy,
isTauTy, tyVarsOfType, tyVarsOfTypes,
- splitForAllTy_maybe, splitAlgTyConApp, splitAlgTyConApp_maybe
- )
-import TyVar ( emptyTyVarEnv, zipTyVarEnv,
- elementOfTyVarSet, mkTyVarSet, tyVarSetToList
+ isForAllTy, splitAlgTyConApp, splitAlgTyConApp_maybe,
+ boxedTypeKind, openTypeKind, mkArrowKind,
+ substFlexiTheta
)
+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 Unify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy )
-import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
+import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy,
+ unifyUnboxedTupleTy )
+import Unique ( cCallableClassKey, cReturnableClassKey,
enumFromClassOpKey, enumFromThenClassOpKey,
enumFromToClassOpKey, enumFromThenToClassOpKey,
thenMClassOpKey, zeroClassOpKey, returnMClassOpKey
)
import Outputable
-import PprType ( GenType, GenTyVar ) -- Instances
import Maybes ( maybeToBool )
import ListSetOps ( minusList )
import Util
\end{code}
+%************************************************************************
+%* *
+\subsection{Main wrappers}
+%* *
+%************************************************************************
+
\begin{code}
-tcExpr :: RenamedHsExpr -- Expession to type check
- -> TcType s -- Expected type (could be a type variable)
- -> TcM s (TcExpr s, LIE s)
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcType s -- Expected type (could be a polytpye)
+ -> TcM s (TcExpr s, LIE s)
+
+tcExpr expr ty | isForAllTy ty = -- Polymorphic case
+ tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) ->
+ returnTc (expr', lie)
+
+ | otherwise = -- Monomorphic case
+ tcMonoExpr expr ty
+\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 s -- Expected type
+ -> TcM s (TcExpr s, LIE s, -- Generalised expr with expected type, and LIE
+ TcExpr s, TcTauType s, LIE s) -- 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
+ tcExtendGlobalTyVars (mkVarSet sig_tyvars) (
+ tcMonoExpr arg sig_tau
+ ) `thenTc` \ (arg', lie_arg) ->
+
+ -- 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.
+
+ tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) $
+ tcAddErrCtxtM (sigCtxt (text "an expression") sig_tau) $
+
+ 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 )
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcExpr (HsVar name) res_ty
+tcMonoExpr :: RenamedHsExpr -- Expession to type check
+ -> TcTauType s -- Expected type (could be a type variable)
+ -> TcM s (TcExpr s, LIE s)
+
+tcMonoExpr (HsVar name) res_ty
= tcId name `thenNF_Tc` \ (expr', lie, id_ty) ->
unifyTauTy res_ty id_ty `thenTc_`
Overloaded literals.
\begin{code}
-tcExpr (HsLit (HsInt i)) res_ty
+tcMonoExpr (HsLit (HsInt i)) res_ty
= newOverloadedLit (LiteralOrigin (HsInt i))
(OverloadedIntegral i)
res_ty `thenNF_Tc` \ stuff ->
returnTc stuff
-tcExpr (HsLit (HsFrac f)) res_ty
+tcMonoExpr (HsLit (HsFrac f)) res_ty
= newOverloadedLit (LiteralOrigin (HsFrac f))
(OverloadedFractional f)
res_ty `thenNF_Tc` \ stuff ->
returnTc stuff
-tcExpr (HsLit lit@(HsLitLit s)) res_ty
+tcMonoExpr (HsLit lit@(HsLitLit s)) res_ty
= tcLookupClassByKey cCallableClassKey `thenNF_Tc` \ cCallableClass ->
newDicts (LitLitOrigin (_UNPK_ s))
[(cCallableClass, [res_ty])] `thenNF_Tc` \ (dicts, _) ->
Primitive literals:
\begin{code}
-tcExpr (HsLit lit@(HsCharPrim c)) res_ty
+tcMonoExpr (HsLit lit@(HsCharPrim c)) res_ty
= unifyTauTy res_ty charPrimTy `thenTc_`
returnTc (HsLitOut lit charPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsStringPrim s)) res_ty
+tcMonoExpr (HsLit lit@(HsStringPrim s)) res_ty
= unifyTauTy res_ty addrPrimTy `thenTc_`
returnTc (HsLitOut lit addrPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsIntPrim i)) res_ty
+tcMonoExpr (HsLit lit@(HsIntPrim i)) res_ty
= unifyTauTy res_ty intPrimTy `thenTc_`
returnTc (HsLitOut lit intPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsFloatPrim f)) res_ty
+tcMonoExpr (HsLit lit@(HsFloatPrim f)) res_ty
= unifyTauTy res_ty floatPrimTy `thenTc_`
returnTc (HsLitOut lit floatPrimTy, emptyLIE)
-tcExpr (HsLit lit@(HsDoublePrim d)) res_ty
+tcMonoExpr (HsLit lit@(HsDoublePrim d)) res_ty
= unifyTauTy res_ty doublePrimTy `thenTc_`
returnTc (HsLitOut lit doublePrimTy, emptyLIE)
\end{code}
Unoverloaded literals:
\begin{code}
-tcExpr (HsLit lit@(HsChar c)) res_ty
+tcMonoExpr (HsLit lit@(HsChar c)) res_ty
= unifyTauTy res_ty charTy `thenTc_`
returnTc (HsLitOut lit charTy, emptyLIE)
-tcExpr (HsLit lit@(HsString str)) res_ty
+tcMonoExpr (HsLit lit@(HsString str)) res_ty
= unifyTauTy res_ty stringTy `thenTc_`
returnTc (HsLitOut lit stringTy, emptyLIE)
\end{code}
%************************************************************************
\begin{code}
-tcExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go
- = tcExpr expr res_ty
+tcMonoExpr (HsPar expr) res_ty -- preserve parens so printing needn't guess where they go
+ = tcMonoExpr expr res_ty
-- 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.
-tcExpr (NegApp (HsLit (HsInt i)) neg) res_ty
- = tcExpr (HsLit (HsInt (-i))) res_ty
+tcMonoExpr (NegApp (HsLit (HsInt i)) neg) res_ty
+ = tcMonoExpr (HsLit (HsInt (-i))) res_ty
-tcExpr (NegApp expr neg) res_ty
- = tcExpr (HsApp neg expr) res_ty
+tcMonoExpr (NegApp expr neg) res_ty
+ = tcMonoExpr (HsApp neg expr) res_ty
-tcExpr (HsLam match) res_ty
- = tcMatchExpected [] res_ty match `thenTc` \ (match',lie) ->
+tcMonoExpr (HsLam match) res_ty
+ = tcMatchExpected match res_ty LambdaBody `thenTc` \ (match',lie) ->
returnTc (HsLam match', lie)
-tcExpr (HsApp e1 e2) res_ty = accum e1 [e2]
+tcMonoExpr (HsApp e1 e2) res_ty = accum e1 [e2]
where
accum (HsApp e1 e2) args = accum e1 (e2:args)
accum fun args
returnTc (foldl HsApp fun' args', lie)
-- equivalent to (op e1) e2:
-tcExpr (OpApp arg1 op fix arg2) res_ty
+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)
\end{code}
-- or just
-- op e
-tcExpr in_expr@(SectionL arg op) res_ty
+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
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcExpr in_expr@(SectionR op expr) res_ty
+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) ->
- tcExpr expr arg2_ty `thenTc` \ (expr',lie2) ->
+ 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}
later use.
\begin{code}
-tcExpr (CCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty
+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 `thenTc` \ (_,_,ioTyCon) ->
-
let
new_arg_dict (arg, arg_ty)
= newDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
in
-- Arguments
- mapNF_Tc (\ _ -> newTyVarTy mkTypeKind) [1..(length args)] `thenNF_Tc` \ ty_vars ->
- tcExprs args ty_vars `thenTc` \ (args', args_lie) ->
+ mapNF_Tc (\ _ -> newTyVarTy openTypeKind)
+ [1..(length args)] `thenNF_Tc` \ ty_vars ->
+ tcMonoExprs args ty_vars `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 mkBoxedTypeKind `thenNF_Tc` \ result_ty ->
+ newTyVarTy boxedTypeKind `thenNF_Tc` \ result_ty ->
let
io_result_ty = mkTyConApp ioTyCon [result_ty]
+ [ioDataCon] = tyConDataCons ioTyCon
in
- case tyConDataCons ioTyCon of { [ioDataCon] ->
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 ty_vars) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
+ mapNF_Tc new_arg_dict (zipEqual "tcMonoExpr:CCall" args ty_vars) `thenNF_Tc` \ ccarg_dicts_s ->
+ newDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
- returnTc (HsApp (HsVar (RealId ioDataCon) `TyApp` [result_ty])
- (CCall lbl args' may_gc is_asm io_result_ty),
+ returnTc (HsApp (HsVar (RealId (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)
- }
\end{code}
\begin{code}
-tcExpr (HsSCC label expr) res_ty
- = tcExpr expr res_ty `thenTc` \ (expr', lie) ->
+tcMonoExpr (HsSCC label expr) res_ty
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
returnTc (HsSCC label expr', lie)
-tcExpr (HsLet binds expr) res_ty
+tcMonoExpr (HsLet binds expr) res_ty
= tcBindsAndThen
combiner
binds -- Bindings to check
- (tc_expr) `thenTc` \ (expr', lie) ->
+ tc_expr `thenTc` \ (expr', lie) ->
returnTc (expr', lie)
where
- tc_expr = tcExpr expr res_ty `thenTc` \ (expr', lie) ->
+ tc_expr = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
returnTc (expr', lie)
combiner is_rec bind expr = HsLet (MonoBind bind [] is_rec) expr
-tcExpr in_expr@(HsCase scrut matches src_loc) res_ty
+tcMonoExpr in_expr@(HsCase scrut matches src_loc) res_ty
= tcAddSrcLoc src_loc $
tcAddErrCtxt (caseCtxt in_expr) $
tcMatchesCase res_ty matches `thenTc` \ (scrut_ty, matches', lie2) ->
tcAddErrCtxt (caseScrutCtxt scrut) (
- tcExpr scrut scrut_ty
+ tcMonoExpr scrut scrut_ty
) `thenTc` \ (scrut',lie1) ->
returnTc (HsCase scrut' matches' src_loc, plusLIE lie1 lie2)
-tcExpr (HsIf pred b1 b2 src_loc) res_ty
+tcMonoExpr (HsIf pred b1 b2 src_loc) res_ty
= tcAddSrcLoc src_loc $
tcAddErrCtxt (predCtxt pred) (
- tcExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
+ tcMonoExpr pred boolTy ) `thenTc` \ (pred',lie1) ->
- tcExpr b1 res_ty `thenTc` \ (b1',lie2) ->
- tcExpr b2 res_ty `thenTc` \ (b2',lie3) ->
+ 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 do_or_lc stmts src_loc) res_ty
+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 in_expr@(ExplicitList exprs) res_ty -- Non-empty list
+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) $
- tcExpr expr elt_ty
-
-tcExpr (ExplicitTuple exprs) res_ty
- = unifyTupleTy (length exprs) res_ty `thenTc` \ arg_tys ->
- mapAndUnzipTc (\ (expr, arg_ty) -> tcExpr expr arg_ty)
+ 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', plusLIEs lies)
+ `thenTc` \ (exprs', lies) ->
+ returnTc (ExplicitTuple exprs' boxed, plusLIEs lies)
-tcExpr (RecordCon con_name _ rbinds) res_ty
- = tcLookupGlobalValue con_name `thenNF_Tc` \ con_id ->
- tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
+tcMonoExpr (RecordCon con_name rbinds) res_ty
+ = tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
let
(_, record_ty) = splitFunTys con_tau
in
unifyTauTy res_ty record_ty `thenTc_`
-- Check that the record bindings match the constructor
+ tcLookupDataCon con_name `thenTc` \ (data_con, _, _) ->
let
- bad_fields = badFields rbinds con_id
+ bad_fields = badFields rbinds data_con
in
- checkTc (null bad_fields) (badFieldsCon con_id bad_fields) `thenTc_`
+ mapNF_Tc (addErrTc . badFieldCon con_name) bad_fields `thenNF_Tc_`
-- Typecheck the record bindings
-- (Do this after checkRecordFields in case there's a field that
-- doesn't match the constructor.)
tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
- returnTc (RecordCon (RealId con_id) con_expr rbinds', con_lie `plusLIE` rbinds_lie)
+ returnTc (RecordConOut data_con con_expr rbinds', con_lie `plusLIE` rbinds_lie)
-- The main complication with RecordUpd is that we need to explicitly
--
-- All this is done in STEP 4 below.
-tcExpr (RecordUpd record_expr rbinds) res_ty
+tcMonoExpr (RecordUpd record_expr rbinds) res_ty
= tcAddErrCtxt recordUpdCtxt $
-- STEP 1
common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
mk_inst_ty (tyvar, result_inst_ty)
- | tyvar `elementOfTyVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
- | otherwise = newTyVarTy mkBoxedTypeKind -- Fresh type
+ | tyvar `elemVarSet` common_tyvars = returnNF_Tc result_inst_ty -- Same as result type
+ | otherwise = newTyVarTy boxedTypeKind -- Fresh type
in
mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
let
record_ty = mkTyConApp tycon inst_tys
in
- tcExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
+ tcMonoExpr record_expr record_ty `thenTc` \ (record_expr', record_lie) ->
-- STEP 6
-- Figure out the LIE we need. We have to generate some
-- union the ones that could participate in the update.
let
(tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
- inst_env = zipTyVarEnv tyvars result_inst_tys
+ inst_env = zipVarEnv tyvars result_inst_tys
+ theta' = substFlexiTheta inst_env theta
in
- tcInstTheta inst_env theta `thenNF_Tc` \ theta' ->
newDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
-- Phew!
returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds',
con_lie `plusLIE` record_lie `plusLIE` rbinds_lie)
-tcExpr (ArithSeqIn seq@(From expr)) res_ty
+tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
= unifyListTy res_ty `thenTc` \ elt_ty ->
- tcExpr expr elt_ty `thenTc` \ (expr', lie1) ->
+ tcMonoExpr expr elt_ty `thenTc` \ (expr', lie1) ->
tcLookupGlobalValueByKey enumFromClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'),
lie1 `plusLIE` lie2)
-tcExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
unifyListTy res_ty `thenTc` \ elt_ty ->
- tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalValueByKey enumFromThenClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
(RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
(FromThen expr1' expr2'),
lie1 `plusLIE` lie2 `plusLIE` lie3)
-tcExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
unifyListTy res_ty `thenTc` \ elt_ty ->
- tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalValueByKey enumFromToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
(RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
(FromTo expr1' expr2'),
lie1 `plusLIE` lie2 `plusLIE` lie3)
-tcExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
unifyListTy res_ty `thenTc` \ elt_ty ->
- tcExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
- tcExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
- tcExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
+ tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
+ tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
+ tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
tcLookupGlobalValueByKey enumFromThenToClassOpKey `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
(RealId sel_id) [elt_ty] `thenNF_Tc` \ (lie4, eft_id) ->
%************************************************************************
\begin{code}
-tcExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
= tcSetErrCtxt (exprSigCtxt in_expr) $
- tcHsType poly_ty `thenTc` \ sigma_sig ->
-
- -- Check the tau-type part
- tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' ->
- let
- (sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
- in
-
- -- Type check the expression, expecting the signature type
- tcExtendGlobalTyVars sig_tyvars' (
- tcExpr expr sig_tau'
- ) `thenTc` \ (texpr, lie) ->
-
- -- Check the type variables of the signature,
- -- *after* typechecking the expression
- checkSigTyVars sig_tyvars' sig_tau' `thenTc` \ zonked_sig_tyvars ->
-
- -- Check overloading constraints
- newDicts SignatureOrigin sig_theta' `thenNF_Tc` \ (sig_dicts, _) ->
- tcSimplifyAndCheck
- (ptext SLIT("the type signature") <+> quotes (ppr sigma_sig))
- (mkTyVarSet zonked_sig_tyvars)
- sig_dicts lie
- `thenTc_`
-
- -- 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 sig_tau' `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)
-
+ tcHsTcType 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)
\end{code}
Typecheck expression which in most cases will be an Id.
= case id_expr of
HsVar name -> tcId name `thenNF_Tc` \ stuff ->
returnTc stuff
- other -> newTyVarTy mkTypeKind `thenNF_Tc` \ id_ty ->
- tcExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
+ other -> newTyVarTy openTypeKind `thenNF_Tc` \ id_ty ->
+ tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
returnTc (id_expr', lie_id, id_ty)
\end{code}
-- 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
+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
- (exp_args, _) = splitFunTys exp_ty'
- (act_args, _) = splitFunTys act_ty'
+ (env1, exp_ty'') = tidyType tidy_env exp_ty'
+ (env2, act_ty'') = tidyType env1 act_ty'
+ (exp_args, _) = splitFunTys exp_ty''
+ (act_args, _) = splitFunTys 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
in
- returnNF_Tc message
+ returnNF_Tc (env2, message)
split_fun_ty :: TcType s -- The type of the function
tcArg the_fun (arg, expected_arg_ty, arg_no)
= tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
- tcPolyExpr (ptext SLIT("argument type of") <+> quotes (ppr the_fun))
- arg expected_arg_ty
-
-
--- tcPolyExpr is like tcExpr, except that the expected type
--- can be a polymorphic one.
-tcPolyExpr str arg expected_arg_ty
- | not (maybeToBool (splitForAllTy_maybe expected_arg_ty))
- = -- The ordinary, non-rank-2 polymorphic case
tcExpr arg expected_arg_ty
-
- | 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
- -- Type-check the arg and unify with expected type
- tcExpr arg sig_tau `thenTc` \ (arg', lie_arg) ->
-
- -- 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 (tyVarSetToList (tyVarsOfType expected_arg_ty)) $
-
- checkSigTyVars sig_tyvars sig_tau `thenTc` \ zonked_sig_tyvars ->
- newDicts Rank2Origin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) ->
- -- ToDo: better origin
-
- tcSimplifyAndCheck
- str
- (mkTyVarSet zonked_sig_tyvars)
- sig_dicts 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 zonked_sig_tyvars $
- DictLam dict_ids $
- HsLet (MonoBind inst_binds [] Recursive)
- arg'
- , free_insts
- )
\end{code}
+
%************************************************************************
%* *
\subsection{@tcId@ typchecks an identifier occurrence}
case maybe_local of
Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id)
- Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
- tcInstType emptyTyVarEnv (idType id) `thenNF_Tc` \ inst_ty ->
- let
- (tyvars, rho) = splitForAllTys inst_ty
- in
- instantiate_it2 (RealId id) tyvars rho
+ Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
+ tcInstId id `thenNF_Tc` \ (tyvars, theta, tau) ->
+ instantiate_it2 (RealId id) tyvars theta tau
where
-- The instantiate_it loop runs round instantiating the Id.
-- 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
+ tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
+ instantiate_it2 tc_id_occ tyvars theta tau
- instantiate_it2 tc_id_occ tyvars rho
- = tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
- if null theta then -- Is it overloaded?
+ 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` \ (lie1, meth_id) ->
- instantiate_it meth_id tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
- returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
+ 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
-- create type consisting of a fresh monad tyvar
ASSERT( not (null stmts) )
tcAddSrcLoc src_loc $
- newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m ->
- let
- tc_stmts [] = returnTc (([], error "tc_stmts"), emptyLIE)
- tc_stmts (stmt:stmts) = tcStmt tcExpr do_or_lc (mkAppTy m) combine_stmts stmt $
- tc_stmts stmts
-
- combine_stmts stmt@(ReturnStmt _) (Just ty) ([], _) = ([stmt], ty)
- combine_stmts stmt@(ExprStmt e _) (Just ty) ([], _) = ([stmt], ty)
- combine_stmts stmt _ ([], _) = panic "Bad last stmt tcDoStmts"
- combine_stmts stmt _ (stmts, ty) = (stmt:stmts, ty)
- in
- tc_stmts stmts `thenTc` \ ((stmts', result_ty), final_lie) ->
- unifyTauTy res_ty result_ty `thenTc_`
+ 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,
failure_free other_stmt = True
in
returnTc (HsDoOut do_or_lc stmts' return_id then_id zero_id res_ty src_loc,
- final_lie `plusLIE` monad_lie)
-
+ stmts_lie `plusLIE` monad_lie)
\end{code}
-\begin{code}
-tcStmt :: (RenamedHsExpr -> TcType s -> TcM s (TcExpr s, LIE s)) -- This is tcExpr
- -- The sole, disgusting, reason for this parameter
- -- is to get the effect of polymorphic recursion
- -- ToDo: rm when booting with Haskell 1.3
- -> DoOrListComp
- -> (TcType s -> TcType s) -- Relationship type of pat and rhs in pat <- rhs
- -> (TcStmt s -> Maybe (TcType s) -> thing -> thing)
- -> RenamedStmt
- -> TcM s (thing, LIE s)
- -> TcM s (thing, LIE s)
-
-tcStmt tc_expr do_or_lc m combine stmt@(ReturnStmt exp) do_next
- = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True; Guard -> True } )
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
- tc_expr exp exp_ty `thenTc` \ (exp', exp_lie) ->
- returnTc (ReturnStmt exp', exp_lie, m exp_ty)
- ) `thenTc` \ (stmt', stmt_lie, stmt_ty) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' (Just stmt_ty) thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine stmt@(GuardStmt exp src_loc) do_next
- = ASSERT( case do_or_lc of { DoStmt -> False; ListComp -> True; Guard -> True } )
- newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tc_expr exp boolTy `thenTc` \ (exp', exp_lie) ->
- returnTc (GuardStmt exp' src_loc, exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' Nothing thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine stmt@(ExprStmt exp src_loc) do_next
- = ASSERT( case do_or_lc of { DoStmt -> True; ListComp -> False; Guard -> False } )
- newTyVarTy mkTypeKind `thenNF_Tc` \ exp_ty ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- newTyVarTy mkTypeKind `thenNF_Tc` \ tau ->
- let
- -- exp has type (m tau) for some tau (doesn't matter what)
- exp_ty = m tau
- in
- tc_expr exp exp_ty `thenTc` \ (exp', exp_lie) ->
- returnTc (ExprStmt exp' src_loc, exp_lie, exp_ty)
- )) `thenTc` \ (stmt', stmt_lie, stmt_ty) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' (Just stmt_ty) thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine stmt@(BindStmt pat exp src_loc) do_next
- = newMonoIds (collectPatBinders pat) mkBoxedTypeKind $ \ _ ->
- tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
- tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) ->
- tc_expr exp (m pat_ty) `thenTc` \ (exp', exp_lie) ->
-
- -- 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
-
- returnTc (BindStmt pat' exp' src_loc, pat_lie `plusLIE` exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- do_next `thenTc` \ (thing', thing_lie) ->
- returnTc (combine stmt' Nothing thing',
- stmt_lie `plusLIE` thing_lie)
-
-tcStmt tc_expr do_or_lc m combine (LetStmt binds) do_next
- = tcBindsAndThen -- No error context, but a binding group is
- combine' -- rather a large thing for an error context anyway
- binds
- do_next
- where
- combine' is_rec binds' thing' = combine (LetStmt (MonoBind binds' [] is_rec)) Nothing thing'
-\end{code}
%************************************************************************
%* *
Just (record_ty, field_ty) = splitFunTy_maybe tau
in
unifyTauTy expected_record_ty record_ty `thenTc_`
- tcPolyExpr (ptext SLIT("type of field") <+> quotes (ppr field_label))
- rhs field_ty `thenTc` \ (rhs', lie) ->
+ tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) ->
returnTc ((RealId sel_id, rhs', pun_flag), lie)
badFields rbinds data_con
%************************************************************************
%* *
-\subsection{@tcExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcMonoExprs@ typechecks a {\em list} of expressions}
%* *
%************************************************************************
\begin{code}
-tcExprs :: [RenamedHsExpr] -> [TcType s] -> TcM s ([TcExpr s], LIE s)
+tcMonoExprs :: [RenamedHsExpr] -> [TcType s] -> TcM s ([TcExpr s], LIE s)
-tcExprs [] [] = returnTc ([], emptyLIE)
-tcExprs (expr:exprs) (ty:tys)
- = tcExpr expr ty `thenTc` \ (expr', lie1) ->
- tcExprs exprs tys `thenTc` \ (exprs', lie2) ->
+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}
quotes (ppr fun) <> text ", namely"])
4 (quotes (ppr arg))
-stmtCtxt do_or_lc stmt
- = hang (ptext SLIT("In a") <+> whatever <> colon)
- 4 (ppr stmt)
- where
- whatever = case do_or_lc of
- ListComp -> ptext SLIT("list-comprehension qualifier")
- DoStmt -> ptext SLIT("do statement")
- Guard -> ptext SLIT("guard")
-
wrongArgsCtxt too_many_or_few fun args
- = hang (ptext SLIT("Probable cause:") <+> ppr fun
+ = 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))
recordUpdCtxt = ptext SLIT("In a record update construct")
-badFieldsCon con fields
- = hsep [ptext SLIT("Constructor"), ppr con,
- ptext SLIT("does not have field(s):"), pprQuotedList fields]
-
notSelector field
= hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
\end{code}
projects / ghc-hetmet.git / blobdiff