\section[TcExpr]{Typecheck an expression}
\begin{code}
-module TcExpr ( tcApp, tcExpr, tcMonoExpr, tcPolyExpr, tcId ) where
+module TcExpr ( tcExpr, tcMonoExpr, tcId ) where
#include "HsVersions.h"
import HsSyn ( HsExpr(..), HsLit(..), ArithSeqInfo(..),
- MonoBinds(..), StmtCtxt(..),
- mkMonoBind, nullMonoBinds
+ HsMatchContext(..), HsDoContext(..), mkMonoBind
)
import RnHsSyn ( RenamedHsExpr, RenamedRecordBinds )
-import TcHsSyn ( TcExpr, TcRecordBinds, mkHsTyApp, mkHsLet )
+import TcHsSyn ( TcExpr, TcRecordBinds, simpleHsLitTy )
import TcMonad
-import BasicTypes ( RecFlag(..) )
-
+import TcUnify ( tcSub, tcGen, (<$>),
+ unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy
+ )
+import BasicTypes ( RecFlag(..), isMarkedStrict )
import Inst ( InstOrigin(..),
- LIE, emptyLIE, unitLIE, plusLIE, plusLIEs,
+ LIE, mkLIE, emptyLIE, unitLIE, plusLIE, plusLIEs,
newOverloadedLit, newMethod, newIPDict,
- instOverloadedFun, newDicts, newClassDicts,
- getIPsOfLIE, instToId, ipToId
+ newDicts,
+ instToId, tcInstId
)
import TcBinds ( tcBindsAndThen )
-import TcEnv ( TcTyThing(..), tcInstId,
- tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe,
- tcLookupTyCon, tcLookupDataCon, tcLookup,
- tcExtendGlobalTyVars
+import TcEnv ( tcLookupClass, tcLookupGlobalId, tcLookupGlobal_maybe,
+ tcLookupTyCon, tcLookupDataCon, tcLookupId
)
import TcMatches ( tcMatchesCase, tcMatchLambda, tcStmts )
-import TcMonoType ( tcHsSigType, checkSigTyVars, sigCtxt )
-import TcPat ( badFieldCon, simpleHsLitTy )
-import TcSimplify ( tcSimplifyAndCheck, partitionPredsOfLIE )
-import TcImprove ( tcImprove )
-import TcType ( TcType, TcTauType,
- tcInstTyVars,
- tcInstTcType, tcSplitRhoTy,
- newTyVarTy, newTyVarTys, zonkTcType )
-
-import FieldLabel ( fieldLabelName, fieldLabelType, fieldLabelTyCon )
-import Id ( idType, recordSelectorFieldLabel, isRecordSelector, mkVanillaId )
-import DataCon ( dataConFieldLabels, dataConSig,
- dataConStrictMarks, StrictnessMark(..)
- )
-import Name ( Name, getName )
-import Type ( mkFunTy, mkAppTy, mkTyVarTys, ipName_maybe,
- splitFunTy_maybe, splitFunTys,
- mkTyConApp, splitSigmaTy,
- splitRhoTy,
- isTauTy, tyVarsOfType, tyVarsOfTypes,
- isSigmaTy, splitAlgTyConApp, splitAlgTyConApp_maybe,
+import TcMonoType ( tcHsSigType, UserTypeCtxt(..) )
+import TcPat ( badFieldCon )
+import TcSimplify ( tcSimplifyIPs )
+import TcMType ( tcInstTyVars, newTyVarTy, newTyVarTys, zonkTcType )
+import TcType ( TcType, TcSigmaType, TcPhiType,
+ tcSplitFunTys, tcSplitTyConApp,
+ isSigmaTy, mkFunTy, mkAppTy, mkTyConTy,
+ mkTyConApp, mkClassPred, tcFunArgTy,
+ tyVarsOfTypes,
liftedTypeKind, openTypeKind, mkArrowKind,
+ tcSplitSigmaTy, tcTyConAppTyCon,
tidyOpenType
)
-import TyCon ( TyCon, tyConTyVars )
-import Subst ( mkTopTyVarSubst, substClasses, substTy )
-import VarSet ( elemVarSet, mkVarSet )
-import TysWiredIn ( boolTy )
-import TcUnify ( unifyTauTy, unifyFunTy, unifyListTy, unifyTupleTy )
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( dataConFieldLabels, dataConSig,
+ dataConStrictMarks
+ )
+import Name ( Name )
+import TyCon ( TyCon, tyConTyVars, isAlgTyCon, tyConDataCons )
+import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import VarSet ( elemVarSet )
+import TysWiredIn ( boolTy, mkListTy, listTyCon )
import PrelNames ( cCallableClassName,
cReturnableClassName,
- enumFromName, enumFromThenName,
+ enumFromName, enumFromThenName,
enumFromToName, enumFromThenToName,
thenMName, failMName, returnMName, ioTyConName
)
import Outputable
-import Maybes ( maybeToBool, mapMaybe )
import ListSetOps ( minusList )
import Util
import CmdLineOpts
%************************************************************************
\begin{code}
-tcExpr :: RenamedHsExpr -- Expession to type check
- -> TcType -- Expected type (could be a polytpye)
- -> TcM (TcExpr, LIE)
+tcExpr :: RenamedHsExpr -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM (TcExpr, LIE) -- Generalised expr with expected type, and LIE
-tcExpr expr ty | isSigmaTy ty = -- Polymorphic case
- tcPolyExpr expr ty `thenTc` \ (expr', lie, _, _, _) ->
- returnTc (expr', lie)
+tcExpr expr expected_ty
+ | not (isSigmaTy expected_ty) -- Monomorphic case
+ = tcMonoExpr expr expected_ty
- | otherwise = -- Monomorphic case
- tcMonoExpr expr ty
+ | otherwise
+ = tcGen expected_ty (tcMonoExpr expr) `thenTc` \ (gen_fn, expr', lie) ->
+ returnTc (gen_fn <$> expr', lie)
\end{code}
%************************************************************************
%* *
-\subsection{@tcPolyExpr@ typchecks an application}
+\subsection{The TAUT rules for variables}
%* *
%************************************************************************
\begin{code}
--- tcPolyExpr is like tcMonoExpr, except that the expected type
--- can be a polymorphic one.
-tcPolyExpr :: RenamedHsExpr
- -> TcType -- Expected type
- -> TcM (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
- free_tyvars = tyVarsOfType expected_arg_ty
- 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 free_tyvars $
- tcAddErrCtxtM (sigCtxt sig_msg sig_tyvars sig_theta sig_tau) $
-
- checkSigTyVars sig_tyvars free_tyvars `thenTc` \ zonked_sig_tyvars ->
-
- newDicts SignatureOrigin sig_theta `thenNF_Tc` \ (sig_dicts, dict_ids) ->
- tcImprove (sig_dicts `plusLIE` lie_arg) `thenTc_`
- -- ToDo: better origin
- tcSimplifyAndCheck
- (text "the type signature of an expression")
- (mkVarSet zonked_sig_tyvars)
- sig_dicts lie_arg `thenTc` \ (free_insts, inst_binds) ->
+tcMonoExpr :: RenamedHsExpr -- Expession to type check
+ -> TcPhiType -- Expected type (could be a type variable)
+ -- Definitely no foralls at the top
+ -- Can be a 'hole'.
+ -> TcM (TcExpr, LIE)
- 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 $
- mkHsLet inst_binds $
- arg'
- in
- returnTc ( generalised_arg, free_insts,
- arg', sig_tau, lie_arg )
- where
- sig_msg = ptext SLIT("When checking an expression type signature")
+tcMonoExpr (HsVar name) res_ty
+ = tcId name `thenNF_Tc` \ (expr', lie1, id_ty) ->
+ tcSub res_ty id_ty `thenTc` \ (co_fn, lie2) ->
+ returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
+
+tcMonoExpr (HsIPVar ip) res_ty
+ = -- Implicit parameters must have a *tau-type* not a
+ -- type scheme. We enforce this by creating a fresh
+ -- type variable as its type. (Because res_ty may not
+ -- be a tau-type.)
+ newTyVarTy openTypeKind `thenNF_Tc` \ ip_ty ->
+ newIPDict (IPOcc ip) ip ip_ty `thenNF_Tc` \ (ip', inst) ->
+ tcSub res_ty ip_ty `thenTc` \ (co_fn, lie) ->
+ returnNF_Tc (co_fn <$> HsIPVar ip', lie `plusLIE` unitLIE inst)
\end{code}
+
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{Expressions type signatures}
%* *
%************************************************************************
\begin{code}
-tcMonoExpr :: RenamedHsExpr -- Expession to type check
- -> TcTauType -- Expected type (could be a type variable)
- -> TcM (TcExpr, LIE)
-
-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)
+tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = tcHsSigType ExprSigCtxt poly_ty `thenTc` \ sig_tc_ty ->
+ tcAddErrCtxt (exprSigCtxt in_expr) $
+ tcExpr expr sig_tc_ty `thenTc` \ (expr', lie1) ->
+ tcSub res_ty sig_tc_ty `thenTc` \ (co_fn, lie2) ->
+ returnTc (co_fn <$> expr', lie1 `plusLIE` lie2)
\end{code}
-\begin{code}
-tcMonoExpr (HsIPVar name) res_ty
- -- ZZ What's the `id' used for here...
- = let id = mkVanillaId name res_ty in
- tcGetInstLoc (OccurrenceOf id) `thenNF_Tc` \ loc ->
- newIPDict name res_ty loc `thenNF_Tc` \ ip ->
- returnNF_Tc (HsIPVar (instToId ip), unitLIE ip)
-\end{code}
%************************************************************************
%* *
tcMonoExpr (HsOverLit lit) res_ty = newOverloadedLit (LiteralOrigin lit) lit res_ty
tcMonoExpr (HsPar expr) res_ty = tcMonoExpr expr res_ty
-tcMonoExpr (NegApp expr neg) res_ty
- = tcMonoExpr (HsApp (HsVar neg) expr) res_ty
+tcMonoExpr (NegApp expr neg_name) res_ty
+ = tcMonoExpr (HsApp (HsVar neg_name) expr) res_ty
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)
-
--- 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 `thenTc` \ (op', lie1, op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2) ->
+ tcAddErrCtxt (exprCtxt in_expr) $
+ tcSub res_ty (mkFunTy arg2_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ returnTc (co_fn <$> SectionL arg1' op', lie1 `plusLIE` lie2 `plusLIE` lie3)
-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-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)
+tcMonoExpr in_expr@(SectionR op arg2) res_ty
+ = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2) ->
+ tcAddErrCtxt (exprCtxt in_expr) $
+ tcSub res_ty (mkFunTy arg1_ty op_res_ty) `thenTc` \ (co_fn, lie3) ->
+ returnTc (co_fn <$> SectionR op' arg2', lie1 `plusLIE` lie2 `plusLIE` lie3)
+
+-- equivalent to (op e1) e2:
+
+tcMonoExpr in_expr@(OpApp arg1 op fix arg2) res_ty
+ = tcExpr_id op `thenTc` \ (op', lie1, op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenTc` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenTc` \ (arg1',lie2a) ->
+ tcArg op (arg2, arg2_ty, 2) `thenTc` \ (arg2',lie2b) ->
+ tcAddErrCtxt (exprCtxt in_expr) $
+ tcSub res_ty op_res_ty `thenTc` \ (co_fn, lie3) ->
+ returnTc (OpApp arg1' op' fix arg2',
+ lie1 `plusLIE` lie2a `plusLIE` lie2b `plusLIE` lie3)
\end{code}
The interesting thing about @ccall@ is that it is just a template
later use.
\begin{code}
-tcMonoExpr (HsCCall lbl args may_gc is_asm ignored_fake_result_ty) res_ty
- = -- Get the callable and returnable classes.
+tcMonoExpr e0@(HsCCall lbl args may_gc is_casm ignored_fake_result_ty) res_ty
+
+ = getDOptsTc `thenNF_Tc` \ dflags ->
+
+ checkTc (not (is_casm && dopt_HscLang dflags /= HscC))
+ (vcat [text "_casm_ is only supported when compiling via C (-fvia-C).",
+ text "Either compile with -fvia-C, or, better, rewrite your code",
+ text "to use the foreign function interface. _casm_s are deprecated",
+ text "and support for them may one day disappear."])
+ `thenTc_`
+
+ -- Get the callable and returnable classes.
tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass ->
tcLookupClass cReturnableClassName `thenNF_Tc` \ cReturnableClass ->
tcLookupTyCon ioTyConName `thenNF_Tc` \ ioTyCon ->
let
new_arg_dict (arg, arg_ty)
- = newClassDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
- [(cCallableClass, [arg_ty])] `thenNF_Tc` \ (arg_dicts, _) ->
+ = newDicts (CCallOrigin (_UNPK_ lbl) (Just arg))
+ [mkClassPred cCallableClass [arg_ty]] `thenNF_Tc` \ arg_dicts ->
returnNF_Tc arg_dicts -- Actually a singleton bag
result_origin = CCallOrigin (_UNPK_ lbl) Nothing {- Not an arg -}
in
-- Arguments
- let n_args = length args
- tv_idxs | n_args == 0 = []
- | otherwise = [1..n_args]
+ let tv_idxs | null args = []
+ | otherwise = [1..length args]
in
newTyVarTys (length tv_idxs) openTypeKind `thenNF_Tc` \ arg_tys ->
tcMonoExprs args arg_tys `thenTc` \ (args', args_lie) ->
-- 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 ->
- newClassDicts result_origin [(cReturnableClass, [result_ty])] `thenNF_Tc` \ (ccres_dict, _) ->
- returnTc (HsCCall lbl args' may_gc is_asm io_result_ty,
- foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie)
+ newDicts result_origin [mkClassPred cReturnableClass [result_ty]] `thenNF_Tc` \ ccres_dict ->
+ returnTc (HsCCall lbl args' may_gc is_casm io_result_ty,
+ mkLIE (ccres_dict ++ concat ccarg_dicts_s) `plusLIE` args_lie)
\end{code}
\begin{code}
\end{code}
\begin{code}
-tcMonoExpr 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)
+ returnTc (ExplicitList elt_ty exprs', plusLIEs lies)
where
tc_elt elt_ty expr
= tcAddErrCtxt (listCtxt expr) $
= tcAddErrCtxt (recordConCtxt expr) $
tcId con_name `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
let
- (_, record_ty) = splitFunTys con_tau
- (tycon, ty_args, _) = splitAlgTyConApp record_ty
+ (_, record_ty) = tcSplitFunTys con_tau
+ (tycon, ty_args) = tcSplitTyConApp record_ty
in
- ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty ) )
+ ASSERT( isAlgTyCon tycon )
unifyTauTy res_ty record_ty `thenTc_`
-- Check that the record bindings match the constructor
tcRecordBinds tycon ty_args rbinds `thenTc` \ (rbinds', rbinds_lie) ->
let
- missing_s_fields = missingStrictFields rbinds data_con
+ (missing_s_fields, missing_fields) = missingFields rbinds data_con
in
checkTcM (null missing_s_fields)
(mapNF_Tc (addErrTc . missingStrictFieldCon con_name) missing_s_fields `thenNF_Tc_`
returnNF_Tc ()) `thenNF_Tc_`
- let
- missing_fields = missingFields rbinds data_con
- in
doptsTc Opt_WarnMissingFields `thenNF_Tc` \ warn ->
checkTcM (not (warn && not (null missing_fields)))
(mapNF_Tc ((warnTc True) . missingFieldCon con_name) missing_fields `thenNF_Tc_`
-- STEP 1
-- Figure out the tycon and data cons from the first field name
let
- (Just (AnId sel_id) : _) = maybe_sel_ids
- (_, _, tau) = splitSigmaTy (idType sel_id) -- Selectors can be overloaded
+ -- 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
- Just (data_ty, _) = splitFunTy_maybe tau -- Must succeed since sel_id is a selector
- (tycon, _, data_cons) = splitAlgTyConApp data_ty
+ data_ty = tcFunArgTy tau -- Must succeed since sel_id is a selector
+ tycon = tcTyConAppTyCon data_ty
+ data_cons = tyConDataCons tycon
(con_tyvars, _, _, _, _, _) = dataConSig (head data_cons)
in
tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, _) ->
let
(tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
inst_env = mkTopTyVarSubst tyvars result_inst_tys
- theta' = substClasses inst_env theta
+ theta' = substTheta inst_env theta
in
- newClassDicts RecordUpdOrigin theta' `thenNF_Tc` \ (con_lie, dicts) ->
+ newDicts RecordUpdOrigin theta' `thenNF_Tc` \ dicts ->
-- Phew!
- returnTc (RecordUpdOut record_expr' result_record_ty dicts rbinds',
- con_lie `plusLIE` record_lie `plusLIE` rbinds_lie)
+ returnTc (RecordUpdOut record_expr' record_ty result_record_ty (map instToId dicts) rbinds',
+ mkLIE dicts `plusLIE` record_lie `plusLIE` rbinds_lie)
tcMonoExpr (ArithSeqIn seq@(From expr)) res_ty
= unifyListTy res_ty `thenTc` \ elt_ty ->
tcLookupGlobalId enumFromName `thenNF_Tc` \ sel_id ->
newMethod (ArithSeqOrigin seq)
- sel_id [elt_ty] `thenNF_Tc` \ (lie2, enum_from_id) ->
+ sel_id [elt_ty] `thenNF_Tc` \ enum_from ->
- returnTc (ArithSeqOut (HsVar enum_from_id) (From expr'),
- lie1 `plusLIE` lie2)
+ returnTc (ArithSeqOut (HsVar (instToId enum_from)) (From expr'),
+ lie1 `plusLIE` unitLIE enum_from)
tcMonoExpr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalId enumFromThenName `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_then_id) ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_then ->
- returnTc (ArithSeqOut (HsVar enum_from_then_id)
- (FromThen expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3)
+ returnTc (ArithSeqOut (HsVar (instToId enum_from_then))
+ (FromThen expr1' expr2'),
+ lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_then)
tcMonoExpr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
tcMonoExpr expr1 elt_ty `thenTc` \ (expr1',lie1) ->
tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcLookupGlobalId enumFromToName `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie3, enum_from_to_id) ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ enum_from_to ->
- returnTc (ArithSeqOut (HsVar enum_from_to_id)
+ returnTc (ArithSeqOut (HsVar (instToId enum_from_to))
(FromTo expr1' expr2'),
- lie1 `plusLIE` lie2 `plusLIE` lie3)
+ lie1 `plusLIE` lie2 `plusLIE` unitLIE enum_from_to)
tcMonoExpr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
= tcAddErrCtxt (arithSeqCtxt in_expr) $
tcMonoExpr expr2 elt_ty `thenTc` \ (expr2',lie2) ->
tcMonoExpr expr3 elt_ty `thenTc` \ (expr3',lie3) ->
tcLookupGlobalId enumFromThenToName `thenNF_Tc` \ sel_id ->
- newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ (lie4, eft_id) ->
+ newMethod (ArithSeqOrigin seq) sel_id [elt_ty] `thenNF_Tc` \ eft ->
- returnTc (ArithSeqOut (HsVar eft_id)
- (FromThenTo expr1' expr2' expr3'),
- lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` lie4)
+ returnTc (ArithSeqOut (HsVar (instToId eft))
+ (FromThenTo expr1' expr2' expr3'),
+ lie1 `plusLIE` lie2 `plusLIE` lie3 `plusLIE` unitLIE eft)
\end{code}
%************************************************************************
%* *
-\subsection{Expressions type signatures}
+\subsection{Implicit Parameter bindings}
%* *
%************************************************************************
\begin{code}
-tcMonoExpr in_expr@(ExprWithTySig expr poly_ty) res_ty
- = tcSetErrCtxt (exprSigCtxt in_expr) $
- tcHsSigType poly_ty `thenTc` \ sig_tc_ty ->
-
- if not (isSigmaTy 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}
-
-Implicit Parameter bindings.
-
-\begin{code}
tcMonoExpr (HsWith expr binds) res_ty
- = tcMonoExpr expr res_ty `thenTc` \ (expr', lie) ->
- tcIPBinds binds `thenTc` \ (binds', types, lie2) ->
- partitionPredsOfLIE isBound lie `thenTc` \ (ips, lie', dict_binds) ->
- let expr'' = if nullMonoBinds dict_binds
- then expr'
- else HsLet (mkMonoBind (revBinds dict_binds) [] NonRecursive)
- expr'
- in
- tcCheckIPBinds binds' types ips `thenTc_`
- returnTc (HsWith expr'' binds', lie' `plusLIE` lie2)
- where isBound p
- = case ipName_maybe p of
- Just n -> n `elem` names
- Nothing -> False
- names = map fst binds
- -- revBinds is used because tcSimplify outputs the bindings
- -- out-of-order. it's not a problem elsewhere because these
- -- bindings are normally used in a recursive let
- -- ZZ probably need to find a better solution
- revBinds (b1 `AndMonoBinds` b2) =
- (revBinds b2) `AndMonoBinds` (revBinds b1)
- revBinds b = b
-
-tcIPBinds ((name, expr) : binds)
- = newTyVarTy openTypeKind `thenTc` \ ty ->
- tcGetSrcLoc `thenTc` \ loc ->
- let id = ipToId name ty loc in
- tcMonoExpr expr ty `thenTc` \ (expr', lie) ->
- zonkTcType ty `thenTc` \ ty' ->
- tcIPBinds binds `thenTc` \ (binds', types, lie2) ->
- returnTc ((id, expr') : binds', ty : types, lie `plusLIE` lie2)
-tcIPBinds [] = returnTc ([], [], emptyLIE)
-
-tcCheckIPBinds binds types ips
- = foldrTc tcCheckIPBind (getIPsOfLIE ips) (zip binds types)
-
--- ZZ how do we use the loc?
-tcCheckIPBind bt@((v, _), t1) ((n, t2) : ips) | getName v == n
- = unifyTauTy t1 t2 `thenTc_`
- tcCheckIPBind bt ips `thenTc` \ ips' ->
- returnTc ips'
-tcCheckIPBind bt (ip : ips)
- = tcCheckIPBind bt ips `thenTc` \ ips' ->
- returnTc (ip : ips')
-tcCheckIPBind bt []
- = returnTc []
-\end{code}
-
-Typecheck expression which in most cases will be an Id.
+ = tcMonoExpr expr res_ty `thenTc` \ (expr', expr_lie) ->
+ mapAndUnzip3Tc tcIPBind binds `thenTc` \ (avail_ips, binds', bind_lies) ->
-\begin{code}
-tcExpr_id :: RenamedHsExpr
- -> TcM (TcExpr,
- LIE,
- TcType)
-tcExpr_id id_expr
- = case id_expr of
- HsVar name -> tcId name `thenNF_Tc` \ stuff ->
- returnTc stuff
- other -> newTyVarTy openTypeKind `thenNF_Tc` \ id_ty ->
- tcMonoExpr id_expr id_ty `thenTc` \ (id_expr', lie_id) ->
- returnTc (id_expr', lie_id, id_ty)
+ -- If the binding binds ?x = E, we must now
+ -- discharge any ?x constraints in expr_lie
+ tcSimplifyIPs avail_ips expr_lie `thenTc` \ (expr_lie', dict_binds) ->
+ let
+ expr'' = HsLet (mkMonoBind dict_binds [] Recursive) expr'
+ in
+ returnTc (HsWith expr'' binds', expr_lie' `plusLIE` plusLIEs bind_lies)
+
+tcIPBind (ip, expr)
+ = newTyVarTy openTypeKind `thenTc` \ ty ->
+ tcGetSrcLoc `thenTc` \ loc ->
+ newIPDict (IPBind ip) ip ty `thenNF_Tc` \ (ip', ip_inst) ->
+ tcMonoExpr expr ty `thenTc` \ (expr', lie) ->
+ returnTc (ip_inst, (ip', expr'), lie)
\end{code}
%************************************************************************
tcApp :: RenamedHsExpr -> [RenamedHsExpr] -- Function and args
-> TcType -- Expected result type of application
- -> TcM (TcExpr, [TcExpr], -- Translated fun and args
- LIE)
+ -> TcM (TcExpr, LIE) -- 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
) `thenTc` \ (expected_arg_tys, actual_result_ty) ->
-- Unify with expected result before type-checking the args
+ -- so that the info from res_ty percolates to expected_arg_tys
-- 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_`
+ tcAddErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
+ (tcSub res_ty actual_result_ty) `thenTc` \ (co_fn, lie_res) ->
-- Now typecheck the args
mapAndUnzipTc (tcArg fun)
(zip3 args expected_arg_tys [1..]) `thenTc` \ (args', lie_args_s) ->
- -- 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 actual_result_ty) `thenTc_`
-
- returnTc (fun', args', lie_fun `plusLIE` plusLIEs lie_args_s)
+ returnTc (co_fn <$> foldl HsApp fun' args',
+ lie_res `plusLIE` lie_fun `plusLIE` plusLIEs lie_args_s)
-- If an error happens we try to figure out whether the
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''
+
+ len_act_args = length act_args
+ len_exp_args = length exp_args
- 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
+ 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)
split_fun_ty :: TcType -- The type of the function
- -> Int -- Number of arguments
+ -> Int -- Number of arguments
-> TcM ([TcType], -- Function argument types
- TcType) -- Function result types
+ TcType) -- Function result types
split_fun_ty fun_ty 0
= returnTc ([], fun_ty)
\end{code}
\begin{code}
-tcArg :: RenamedHsExpr -- The function (for error messages)
- -> (RenamedHsExpr, TcType, Int) -- Actual argument and expected arg type
- -> TcM (TcExpr, LIE) -- Resulting argument and LIE
+tcArg :: RenamedHsExpr -- The function (for error messages)
+ -> (RenamedHsExpr, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (TcExpr, LIE) -- Resulting argument and LIE
tcArg the_fun (arg, expected_arg_ty, arg_no)
= tcAddErrCtxt (funAppCtxt the_fun arg arg_no) $
\begin{code}
tcId :: Name -> NF_TcM (TcExpr, LIE, TcType)
+tcId name -- Look up the Id and instantiate its type
+ = tcLookupId name `thenNF_Tc` \ id ->
+ tcInstId id
+\end{code}
-tcId name
- = -- Look up the Id and instantiate its type
- tcLookup name `thenNF_Tc` \ thing ->
- case thing of
- ATcId tc_id -> instantiate_it (OccurrenceOf tc_id) tc_id (idType tc_id)
- AGlobal (AnId id) -> tcInstId id `thenNF_Tc` \ (tyvars, theta, tau) ->
- instantiate_it2 (OccurrenceOf id) id tyvars theta tau
- 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 orig fun ty
- = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) ->
- tcSplitRhoTy rho `thenNF_Tc` \ (theta, tau) ->
- instantiate_it2 orig fun tyvars theta tau
-
- instantiate_it2 orig fun tyvars theta tau
- = if null theta then -- Is it overloaded?
- returnNF_Tc (mkHsTyApp (HsVar fun) arg_tys, emptyLIE, tau)
- else
- -- Yes, it's overloaded
- instOverloadedFun orig fun arg_tys theta tau `thenNF_Tc` \ (fun', lie1) ->
- instantiate_it orig fun' tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
- returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
-
- where
- arg_tys = mkTyVarTys tyvars
+Typecheck expression which in most cases will be an Id.
+
+\begin{code}
+tcExpr_id :: RenamedHsExpr -> TcM (TcExpr, LIE, TcType)
+tcExpr_id (HsVar name) = tcId name
+tcExpr_id expr = newTyVarTy openTypeKind `thenNF_Tc` \ id_ty ->
+ tcMonoExpr expr id_ty `thenTc` \ (expr', lie_id) ->
+ returnTc (expr', lie_id, id_ty)
\end{code}
+
%************************************************************************
%* *
\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
ASSERT( not (null stmts) )
tcAddSrcLoc src_loc $
- newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m ->
- newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty ->
- unifyTauTy res_ty (mkAppTy m elt_ty) `thenTc_`
-
-- If it's a comprehension we're dealing with,
-- force it to be a list comprehension.
-- (as of Haskell 98, monad comprehensions are no more.)
(case do_or_lc of
- ListComp -> unifyListTy res_ty `thenTc_` returnTc ()
- _ -> returnTc ()) `thenTc_`
+ ListComp -> unifyListTy res_ty `thenTc` \ elt_ty ->
+ returnNF_Tc (mkTyConTy listTyCon, (mkListTy, elt_ty))
+
+ _ -> newTyVarTy (mkArrowKind liftedTypeKind liftedTypeKind) `thenNF_Tc` \ m_ty ->
+ newTyVarTy liftedTypeKind `thenNF_Tc` \ elt_ty ->
+ unifyTauTy res_ty (mkAppTy m_ty elt_ty) `thenTc_`
+ returnNF_Tc (m_ty, (mkAppTy m_ty, elt_ty))
+ ) `thenNF_Tc` \ (tc_ty, m_ty) ->
- tcStmts do_or_lc (mkAppTy m) elt_ty src_loc stmts `thenTc` \ ((stmts', _), stmts_lie) ->
+ tcStmts (DoCtxt do_or_lc) m_ty stmts `thenTc` \ (stmts', stmts_lie) ->
-- Build the then and zero methods in case we need them
-- It's important that "then" and "return" appear just once in the final LIE,
tcLookupGlobalId returnMName `thenNF_Tc` \ return_sel_id ->
tcLookupGlobalId thenMName `thenNF_Tc` \ then_sel_id ->
tcLookupGlobalId failMName `thenNF_Tc` \ fail_sel_id ->
- newMethod DoOrigin return_sel_id [m] `thenNF_Tc` \ (return_lie, return_id) ->
- newMethod DoOrigin then_sel_id [m] `thenNF_Tc` \ (then_lie, then_id) ->
- newMethod DoOrigin fail_sel_id [m] `thenNF_Tc` \ (fail_lie, fail_id) ->
+ newMethod DoOrigin return_sel_id [tc_ty] `thenNF_Tc` \ return_inst ->
+ newMethod DoOrigin then_sel_id [tc_ty] `thenNF_Tc` \ then_inst ->
+ newMethod DoOrigin fail_sel_id [tc_ty] `thenNF_Tc` \ fail_inst ->
let
- monad_lie = then_lie `plusLIE` return_lie `plusLIE` fail_lie
+ monad_lie = mkLIE [return_inst, then_inst, fail_inst]
in
- returnTc (HsDoOut do_or_lc stmts' return_id then_id fail_id res_ty src_loc,
+ returnTc (HsDoOut do_or_lc stmts'
+ (instToId return_inst) (instToId then_inst) (instToId fail_inst)
+ res_ty src_loc,
stmts_lie `plusLIE` monad_lie)
\end{code}
-- The caller of tcRecordBinds has already checked
-- that all the fields come from the same type
- tcPolyExpr rhs field_ty `thenTc` \ (rhs', lie, _, _, _) ->
+ tcExpr rhs field_ty `thenTc` \ (rhs', lie) ->
returnTc ((sel_id, rhs', pun_flag), lie)
where
field_names = map fieldLabelName (dataConFieldLabels data_con)
-missingStrictFields rbinds data_con
- = [ fn | fn <- strict_field_names,
- not (fn `elem` field_names_used)
- ]
- where
- field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
- strict_field_names = mapMaybe isStrict field_info
-
- isStrict (fl, MarkedStrict) = Just (fieldLabelName fl)
- isStrict _ = Nothing
-
- field_info = zip (dataConFieldLabels data_con)
- (dataConStrictMarks data_con)
-
missingFields rbinds data_con
- = [ fn | fn <- non_strict_field_names, not (fn `elem` field_names_used) ]
+ | null field_labels = ([], []) -- Not declared as a record;
+ -- But C{} is still valid
+ | otherwise
+ = (missing_strict_fields, other_missing_fields)
where
- field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
-
- -- missing strict fields have already been flagged as
- -- being so, so leave them out here.
- non_strict_field_names = mapMaybe isn'tStrict field_info
-
- isn'tStrict (fl, MarkedStrict) = Nothing
- isn'tStrict (fl, _) = Just (fieldLabelName fl)
-
- field_info = zip (dataConFieldLabels data_con)
- (dataConStrictMarks data_con)
+ missing_strict_fields
+ = [ fl | (fl, str) <- field_info,
+ isMarkedStrict str,
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+ other_missing_fields
+ = [ fl | (fl, str) <- field_info,
+ not (isMarkedStrict str),
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+ field_names_used = [ field_name | (field_name, _, _) <- rbinds ]
+ field_labels = dataConFieldLabels data_con
+
+ field_info = zipEqual "missingFields"
+ field_labels
+ (dropList ex_theta (dataConStrictMarks data_con))
+ -- The 'drop' is because dataConStrictMarks
+ -- includes the existential dictionaries
+ (_, _, _, ex_theta, _, _) = dataConSig data_con
\end{code}
%************************************************************************
tcLit :: HsLit -> TcType -> TcM (TcExpr, LIE)
tcLit (HsLitLit s _) res_ty
= tcLookupClass cCallableClassName `thenNF_Tc` \ cCallableClass ->
- newClassDicts (LitLitOrigin (_UNPK_ s))
- [(cCallableClass,[res_ty])] `thenNF_Tc` \ (dicts, _) ->
- returnTc (HsLit (HsLitLit s res_ty), dicts)
+ newDicts (LitLitOrigin (_UNPK_ s))
+ [mkClassPred cCallableClass [res_ty]] `thenNF_Tc` \ dicts ->
+ returnTc (HsLit (HsLitLit s res_ty), mkLIE dicts)
tcLit lit res_ty
= unifyTauTy res_ty (simpleHsLitTy lit) `thenTc_`
Mini-utils:
-\begin{code}
-pp_nest_hang :: String -> SDoc -> SDoc
-pp_nest_hang lbl stuff = nest 2 (hang (text lbl) 4 stuff)
-\end{code}
-
Boring and alphabetical:
\begin{code}
arithSeqCtxt expr
predCtxt expr
= hang (ptext SLIT("In the predicate 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)
+exprCtxt expr
+ = hang (ptext SLIT("In the expression:")) 4 (ppr expr)
funAppCtxt fun arg arg_no
= hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
notSelector field
= hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
-missingStrictFieldCon :: Name -> Name -> SDoc
+missingStrictFieldCon :: Name -> FieldLabel -> SDoc
missingStrictFieldCon con field
= hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
ptext SLIT("does not have the required strict field"), quotes (ppr field)]
-missingFieldCon :: Name -> Name -> SDoc
+missingFieldCon :: Name -> FieldLabel -> SDoc
missingFieldCon con field
= hsep [ptext SLIT("Field") <+> quotes (ppr field),
ptext SLIT("is not initialised")]
projects / ghc-hetmet.git / blobdiff