\begin{code}
#include "HsVersions.h"
-module TcExpr ( tcExpr ) where
+module TcExpr ( tcExpr, tcStmt, tcId ) where
-import Ubiq
+IMP_Ubiq()
-import HsSyn ( HsExpr(..), Qual(..), Stmt(..),
- HsBinds(..), Bind(..), MonoBinds(..),
+import HsSyn ( HsExpr(..), Stmt(..), DoOrListComp(..),
+ HsBinds(..), MonoBinds(..),
+ SYN_IE(RecFlag), nonRecursive,
ArithSeqInfo(..), HsLit(..), Sig, GRHSsAndBinds,
- Match, Fake, InPat, OutPat, PolyType,
- irrefutablePat, collectPatBinders )
-import RnHsSyn ( RenamedHsExpr(..), RenamedQual(..),
- RenamedStmt(..), RenamedRecordBinds(..)
+ Match, Fake, InPat, OutPat, HsType, Fixity,
+ pprParendExpr, failureFreePat, collectPatBinders )
+import RnHsSyn ( SYN_IE(RenamedHsExpr),
+ SYN_IE(RenamedStmt), SYN_IE(RenamedRecordBinds)
)
-import TcHsSyn ( TcExpr(..), TcQual(..), TcStmt(..),
- TcIdOcc(..), TcRecordBinds(..),
+import TcHsSyn ( SYN_IE(TcExpr), SYN_IE(TcStmt),
+ TcIdOcc(..), SYN_IE(TcRecordBinds),
mkHsTyApp
)
import TcMonad
import Inst ( Inst, InstOrigin(..), OverloadedLit(..),
- LIE(..), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
+ SYN_IE(LIE), emptyLIE, plusLIE, plusLIEs, newOverloadedLit,
newMethod, newMethodWithGivenTy, newDicts )
-import TcBinds ( tcBindsAndThen )
+import TcBinds ( tcBindsAndThen, checkSigTyVars )
import TcEnv ( tcLookupLocalValue, tcLookupGlobalValue, tcLookupClassByKey,
tcLookupGlobalValueByKey, newMonoIds, tcGetGlobalTyVars,
- tcGlobalOcc
+ tcExtendGlobalTyVars, tcLookupGlobalValueMaybe
)
+import SpecEnv ( SpecEnv )
import TcMatches ( tcMatchesCase, tcMatch )
-import TcMonoType ( tcPolyType )
+import TcMonoType ( tcHsType )
import TcPat ( tcPat )
import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-import TcType ( TcType(..), TcMaybe(..),
- tcInstType, tcInstTcType, tcInstTyVars,
- newTyVarTy, zonkTcTyVars, zonkTcType )
+import TcType ( SYN_IE(TcType), TcMaybe(..),
+ tcInstId, tcInstType, tcInstSigTcType, tcInstTyVars,
+ tcInstSigType, tcInstTcType, tcInstTheta, tcSplitRhoTy,
+ newTyVarTy, newTyVarTys, zonkTcTyVars, zonkTcType )
import TcKind ( TcKind )
-import Class ( Class(..), getClassSig )
-import FieldLabel ( fieldLabelName )
-import Id ( Id(..), GenId, idType, dataConFieldLabels )
+import Class ( SYN_IE(Class) )
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType )
+import Id ( idType, dataConFieldLabels, dataConSig, recordSelectorFieldLabel,
+ isRecordSelector,
+ SYN_IE(Id), GenId
+ )
import Kind ( Kind, mkBoxedTypeKind, mkTypeKind, mkArrowKind )
-import GenSpecEtc ( checkSigTyVars, checkSigTyVarsGivenGlobals )
-import PrelInfo ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy, addrTy,
- boolTy, charTy, stringTy, mkListTy,
- mkTupleTy, mkPrimIoTy )
-import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys,
- getTyVar_maybe, getFunTy_maybe,
+import Name ( Name{-instance Eq-} )
+import Type ( mkFunTy, mkAppTy, mkTyVarTy, mkTyVarTys, mkRhoTy,
+ getTyVar_maybe, getFunTy_maybe, instantiateTy, applyTyCon,
splitForAllTy, splitRhoTy, splitSigmaTy, splitFunTy,
- isTauTy, mkFunTys, tyVarsOfType, getForAllTy_maybe,
- maybeAppDataTyCon
+ isTauTy, mkFunTys, tyVarsOfType, tyVarsOfTypes, getForAllTy_maybe,
+ getAppDataTyCon, maybeAppDataTyCon
+ )
+import TyVar ( GenTyVar, SYN_IE(TyVarSet), unionTyVarSets, elementOfTyVarSet, mkTyVarSet )
+import TysPrim ( intPrimTy, charPrimTy, doublePrimTy,
+ floatPrimTy, addrPrimTy, realWorldTy
+ )
+import TysWiredIn ( addrTy,
+ boolTy, charTy, stringTy, mkListTy,
+ mkTupleTy, mkPrimIoTy, stDataCon
)
-import TyVar ( GenTyVar, TyVarSet(..), unionTyVarSets, mkTyVarSet )
import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy )
import Unique ( Unique, cCallableClassKey, cReturnableClassKey,
enumFromClassOpKey, enumFromThenClassOpKey,
enumFromToClassOpKey, enumFromThenToClassOpKey,
- monadClassKey, monadZeroClassKey )
-
-import Name ( Name ) -- Instance
-import Outputable ( interpp'SP )
+ thenMClassOpKey, zeroClassOpKey, returnMClassOpKey
+ )
+import Outputable ( speakNth, interpp'SP, Outputable(..) )
import PprType ( GenType, GenTyVar ) -- Instances
import Maybes ( maybeToBool )
import Pretty
+import ListSetOps ( minusList )
import Util
\end{code}
\begin{code}
tcExpr (HsVar name)
- = tcId name `thenTc` \ (expr', lie, res_ty) ->
+ = tcId name `thenNF_Tc` \ (expr', lie, res_ty) ->
-- Check that the result type doesn't have any nested for-alls.
-- For example, a "build" on its own is no good; it must be
%************************************************************************
\begin{code}
+tcExpr (HsPar expr) -- preserve parens so printing needn't guess where they go
+ = tcExpr expr
+
+tcExpr (NegApp expr neg) = tcExpr (HsApp neg expr)
+
tcExpr (HsLam match)
= tcMatch match `thenTc` \ (match',lie,ty) ->
returnTc (HsLam match', lie, ty)
returnTc (foldl HsApp fun' args', lie, res_ty)
-- equivalent to (op e1) e2:
-tcExpr (OpApp arg1 op arg2)
+tcExpr (OpApp arg1 op fix arg2)
= tcApp op [arg1,arg2] `thenTc` \ (op', [arg1', arg2'], lie, res_ty) ->
- returnTc (OpApp arg1' op' arg2', lie, res_ty)
+ returnTc (OpApp arg1' op' fix arg2', lie, res_ty)
\end{code}
Note that the operators in sections are expected to be binary, and
newTyVarTy mkTypeKind `thenNF_Tc` \ ty1 ->
newTyVarTy mkTypeKind `thenNF_Tc` \ ty2 ->
tcAddErrCtxt (sectionRAppCtxt in_expr) $
- unifyTauTy op_ty (mkFunTys [ty1, expr_ty] ty2) `thenTc_`
+ unifyTauTy (mkFunTys [ty1, expr_ty] ty2) op_ty `thenTc_`
returnTc (SectionR op' expr', lie1 `plusLIE` lie2, mkFunTy ty1 ty2)
\end{code}
-- Construct the extra insts, which encode the
-- constraints on the argument and result types.
- mapNF_Tc new_arg_dict (args `zip` arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
- newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) ->
+ mapNF_Tc new_arg_dict (zipEqual "tcExpr:CCall" args arg_tys) `thenNF_Tc` \ ccarg_dicts_s ->
+ newDicts result_origin [(cReturnableClass, result_ty)] `thenNF_Tc` \ (ccres_dict, _) ->
- returnTc (CCall lbl args' may_gc is_asm result_ty,
+ returnTc (HsApp (HsVar (RealId stDataCon) `TyApp` [realWorldTy, result_ty])
+ (CCall lbl args' may_gc is_asm result_ty),
+ -- do the wrapping in the newtype constructor here
foldr plusLIE ccres_dict ccarg_dicts_s `plusLIE` args_lie,
mkPrimIoTy result_ty)
\end{code}
tcExpr (HsLet binds expr)
= tcBindsAndThen
- HsLet -- The combiner
+ combiner
binds -- Bindings to check
- (tcExpr expr) -- Typechecker for the expression
+ (tc_expr expr) `thenTc` \ ((expr', ty), lie) ->
+ returnTc (expr', lie, ty)
+ where
+ tc_expr expr = tcExpr expr `thenTc` \ (expr', lie, ty) ->
+ returnTc ((expr',ty), lie)
+ combiner is_rec bind (expr, ty) = (HsLet (MonoBind bind [] is_rec) expr, ty)
tcExpr in_expr@(HsCase expr matches src_loc)
= tcAddSrcLoc src_loc $
tcExpr pred `thenTc` \ (pred',lie1,predTy) ->
tcAddErrCtxt (predCtxt pred) (
- unifyTauTy predTy boolTy
+ unifyTauTy boolTy predTy
) `thenTc_`
tcExpr b1 `thenTc` \ (b1',lie2,result_ty) ->
unifyTauTy result_ty b2Ty `thenTc_`
returnTc (HsIf pred' b1' b2' src_loc, plusLIE lie1 (plusLIE lie2 lie3), result_ty)
-
-tcExpr (ListComp expr quals)
- = tcListComp expr quals `thenTc` \ ((expr',quals'), lie, ty) ->
- returnTc (ListComp expr' quals', lie, ty)
\end{code}
\begin{code}
-tcExpr (HsDo stmts src_loc)
- = -- get the Monad and MonadZero classes
- -- create type consisting of a fresh monad tyvar
- tcAddSrcLoc src_loc $
- newTyVarTy monadKind `thenNF_Tc` \ m ->
- tcDoStmts False m stmts `thenTc` \ ((stmts',monad,mzero), lie, do_ty) ->
-
- -- create dictionaries for monad and possibly monadzero
- (if monad then
- tcLookupClassByKey monadClassKey `thenNF_Tc` \ monadClass ->
- newDicts DoOrigin [(monadClass, m)]
- else
- returnNF_Tc (emptyLIE, [panic "TcExpr: MonadZero dictionary"])
- ) `thenNF_Tc` \ (m_lie, [m_id]) ->
- (if mzero then
- tcLookupClassByKey monadZeroClassKey `thenNF_Tc` \ monadZeroClass ->
- newDicts DoOrigin [(monadZeroClass, m)]
- else
- returnNF_Tc (emptyLIE, [panic "TcExpr: MonadZero dictionary"])
- ) `thenNF_Tc` \ (mz_lie, [mz_id]) ->
-
- returnTc (HsDoOut stmts' m_id mz_id src_loc,
- lie `plusLIE` m_lie `plusLIE` mz_lie,
- do_ty)
- where
- monadKind = mkArrowKind mkBoxedTypeKind mkBoxedTypeKind
+tcExpr expr@(HsDo do_or_lc stmts src_loc)
+ = tcDoStmts do_or_lc stmts src_loc
\end{code}
\begin{code}
-tcExpr (ExplicitList [])
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], emptyLIE, mkListTy tyvar_ty)
-
-
tcExpr in_expr@(ExplicitList exprs) -- Non-empty list
- = tcExprs exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) ->
- tcAddErrCtxt (listCtxt in_expr) $
- unifyTauTyList tys `thenTc_`
- returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty)
+ = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ elt_ty ->
+ mapAndUnzipTc (tc_elt elt_ty) exprs `thenTc` \ (exprs', lies) ->
+ returnTc (ExplicitListOut elt_ty exprs', plusLIEs lies, mkListTy elt_ty)
+ where
+ tc_elt elt_ty expr
+ = tcAddErrCtxt (listCtxt expr) $
+ tcExpr expr `thenTc` \ (expr', lie, expr_ty) ->
+ unifyTauTy elt_ty expr_ty `thenTc_`
+ returnTc (expr', lie)
tcExpr (ExplicitTuple exprs)
= tcExprs exprs `thenTc` \ (exprs', lie, tys) ->
returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys)
tcExpr (RecordCon (HsVar con) rbinds)
- = tcGlobalOcc con `thenNF_Tc` \ (con_id, arg_tys, con_rho) ->
+ = tcId con `thenNF_Tc` \ (con_expr, con_lie, con_tau) ->
let
- (con_theta, con_tau) = splitRhoTy con_rho
- (_, record_ty) = splitFunTy con_tau
- con_expr = mkHsTyApp (HsVar (RealId con_id)) arg_tys
+ (_, record_ty) = splitFunTy con_tau
in
- -- TEMPORARY ASSERT
- ASSERT( null con_theta )
-
-- Con is syntactically constrained to be a data constructor
ASSERT( maybeToBool (maybeAppDataTyCon record_ty ) )
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ -- Check that the record bindings match the constructor
+ tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
+ let
+ bad_fields = badFields rbinds con_id
+ in
+ checkTc (null bad_fields) (badFieldsCon con bad_fields) `thenTc_`
- checkTc (checkRecordFields rbinds con_id)
- (badFieldsCon con rbinds) `thenTc_`
+ -- 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 con_expr rbinds', panic "tcExpr:RecordCon:con_lie???" {-con_lie???-} `plusLIE` rbinds_lie, record_ty)
+ returnTc (RecordCon con_expr rbinds', con_lie `plusLIE` rbinds_lie, record_ty)
+
+
+-- The main complication with RecordUpd is that we need to explicitly
+-- handle the *non-updated* fields. Consider:
+--
+-- data T a b = MkT1 { fa :: a, fb :: b }
+-- | MkT2 { fa :: a, fc :: Int -> Int }
+-- | MkT3 { fd :: a }
+--
+-- upd :: T a b -> c -> T a c
+-- upd t x = t { fb = x}
+--
+-- The type signature on upd is correct (i.e. the result should not be (T a b))
+-- because upd should be equivalent to:
+--
+-- upd t x = case t of
+-- MkT1 p q -> MkT1 p x
+-- MkT2 a b -> MkT2 p b
+-- MkT3 d -> error ...
+--
+-- So we need to give a completely fresh type to the result record,
+-- and then constrain it by the fields that are *not* updated ("p" above).
+--
+-- Note that because MkT3 doesn't contain all the fields being updated,
+-- its RHS is simply an error, so it doesn't impose any type constraints
+--
+-- All this is done in STEP 4 below.
tcExpr (RecordUpd record_expr rbinds)
- = tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
- tcRecordBinds record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+ = tcAddErrCtxt recordUpdCtxt $
- -- Check that the field names are plausible
- zonkTcType record_ty `thenNF_Tc` \ record_ty' ->
+ -- STEP 1
+ -- Figure out the tycon and data cons from the first field name
+ ASSERT( not (null rbinds) )
+ let
+ ((first_field_name, _, _) : rest) = rbinds
+ in
+ tcLookupGlobalValueMaybe first_field_name `thenNF_Tc` \ maybe_sel_id ->
+ (case maybe_sel_id of
+ Just sel_id | isRecordSelector sel_id -> returnTc sel_id
+ other -> failTc (notSelector first_field_name)
+ ) `thenTc` \ sel_id ->
let
- maybe_tycon_stuff = maybeAppDataTyCon record_ty'
- Just (tycon, args_tys, data_cons) = maybe_tycon_stuff
+ (_, tau) = splitForAllTy (idType sel_id)
+ Just (data_ty, _) = getFunTy_maybe tau -- Must succeed since sel_id is a selector
+ (tycon, _, data_cons) = getAppDataTyCon data_ty
+ (con_tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
in
- checkTc (maybeToBool maybe_tycon_stuff)
- (panic "TcExpr:Records:mystery error message") `thenTc_`
- checkTc (any (checkRecordFields rbinds) data_cons)
+ tcInstTyVars con_tyvars `thenNF_Tc` \ (_, result_inst_tys, result_inst_env) ->
+
+ -- STEP 2
+ -- Check for bad fields
+ checkTc (any (null . badFields rbinds) data_cons)
(badFieldsUpd rbinds) `thenTc_`
- returnTc (RecordUpd record_expr' rbinds', record_lie `plusLIE` rbinds_lie, record_ty)
+ -- STEP 3
+ -- Typecheck the update bindings.
+ -- (Do this after checking for bad fields in case there's a field that
+ -- doesn't match the constructor.)
+ let
+ result_record_ty = applyTyCon tycon result_inst_tys
+ in
+ tcRecordBinds result_record_ty rbinds `thenTc` \ (rbinds', rbinds_lie) ->
+
+ -- STEP 4
+ -- Use the un-updated fields to find a vector of booleans saying
+ -- which type arguments must be the same in updatee and result.
+ --
+ -- WARNING: this code assumes that all data_cons in a common tycon
+ -- have FieldLabels abstracted over the same tyvars.
+ let
+ upd_field_lbls = [recordSelectorFieldLabel sel_id | (RealId sel_id, _, _) <- rbinds']
+ con_field_lbls_s = map dataConFieldLabels data_cons
+
+ -- A constructor is only relevant to this process if
+ -- it contains all the fields that are being updated
+ relevant_field_lbls_s = filter is_relevant con_field_lbls_s
+ is_relevant con_field_lbls = all (`elem` con_field_lbls) upd_field_lbls
+
+ non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
+ 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
+ in
+ mapNF_Tc mk_inst_ty (zip con_tyvars result_inst_tys) `thenNF_Tc` \ inst_tys ->
+
+ -- STEP 5
+ -- Typecheck the expression to be updated
+ tcExpr record_expr `thenTc` \ (record_expr', record_lie, record_ty) ->
+ unifyTauTy (applyTyCon tycon inst_tys) record_ty `thenTc_`
+
+
+ -- STEP 6
+ -- Figure out the LIE we need. We have to generate some
+ -- dictionaries for the data type context, since we are going to
+ -- do some construction.
+ --
+ -- What dictionaries do we need? For the moment we assume that all
+ -- data constructors have the same context, and grab it from the first
+ -- constructor. If they have varying contexts then we'd have to
+ -- union the ones that could participate in the update.
+ let
+ (tyvars, theta, _, _, _, _) = dataConSig (head data_cons)
+ inst_env = zipEqual "tcExpr:RecordUpd" tyvars result_inst_tys
+ 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,
+ result_record_ty)
+
tcExpr (ArithSeqIn seq@(From expr))
= tcExpr expr `thenTc` \ (expr', lie1, ty) ->
\begin{code}
tcExpr in_expr@(ExprWithTySig expr poly_ty)
= tcExpr expr `thenTc` \ (texpr, lie, tau_ty) ->
- tcPolyType poly_ty `thenTc` \ sigma_sig ->
+ tcHsType poly_ty `thenTc` \ sigma_sig ->
-- Check the tau-type part
tcSetErrCtxt (exprSigCtxt in_expr) $
- tcInstType [] sigma_sig `thenNF_Tc` \ sigma_sig' ->
+ tcInstSigType sigma_sig `thenNF_Tc` \ sigma_sig' ->
let
(sig_tyvars', sig_theta', sig_tau') = splitSigmaTy sigma_sig'
in
- unifyTauTy tau_ty sig_tau' `thenTc_`
+ unifyTauTy sig_tau' tau_ty `thenTc_`
-- Check the type variables of the signature
checkSigTyVars sig_tyvars' sig_tau' `thenTc_`
-- In the HsVar case we go straight to tcId to avoid hitting the
-- rank-2 check, which we check later here anyway
(case fun of
- HsVar name -> tcId name
+ HsVar name -> tcId name `thenNF_Tc` \ stuff -> returnTc stuff
other -> tcExpr fun
) `thenTc` \ (fun', lie_fun, fun_ty) ->
-- 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
- (expected_tyvars, expected_theta, expected_tau) = splitSigmaTy expected_arg_ty
+ (sig_theta, sig_tau) = splitRhoTy sig_rho
in
- ASSERT( null expected_theta ) -- And expected_tyvars are all DontBind things
-
+ ASSERT( null sig_theta ) -- And expected_tyvars are all DontBind things
+
-- Type-check the arg and unify with expected type
tcExpr arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
- unifyTauTy expected_tau actual_arg_ty `thenTc_` (
+ unifyTauTy sig_tau actual_arg_ty `thenTc_`
-- Check that the arg_tyvars havn't been constrained
-- The interesting bit here is that we must include the free variables
-- 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) $
- tcGetGlobalTyVars `thenNF_Tc` \ env_tyvars ->
- zonkTcTyVars (tyVarsOfType expected_arg_ty) `thenNF_Tc` \ free_tyvars ->
- checkSigTyVarsGivenGlobals
- (env_tyvars `unionTyVarSets` free_tyvars)
- expected_tyvars expected_tau `thenTc_`
-
- -- Check that there's no overloading involved
- -- Even if there isn't, there may be some Insts which mention the expected_tyvars,
- -- but which, on simplification, don't actually need a dictionary involving
- -- the tyvar. So we have to do a proper simplification right here.
- tcSimplifyRank2 (mkTyVarSet expected_tyvars)
- lie_arg `thenTc` \ (free_insts, inst_binds) ->
-
- -- This HsLet binds any Insts which came out of the simplification.
- -- It's a bit out of place here, but using AbsBind involves inventing
- -- a couple of new names which seems worse.
- returnTc (TyLam expected_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts)
+
+ tcAddErrCtxt (rank2ArgCtxt arg expected_arg_ty) (
+ tcExtendGlobalTyVars (tyVarsOfType expected_arg_ty) (
+ checkSigTyVars sig_tyvars sig_tau
+ ) `thenTc_`
+
+ -- Check that there's no overloading involved
+ -- Even if there isn't, there may be some Insts which mention the expected_tyvars,
+ -- but which, on simplification, don't actually need a dictionary involving
+ -- the tyvar. So we have to do a proper simplification right here.
+ tcSimplifyRank2 (mkTyVarSet sig_tyvars)
+ lie_arg `thenTc` \ (free_insts, inst_binds) ->
+
+ -- This HsLet binds any Insts which came out of the simplification.
+ -- It's a bit out of place here, but using AbsBind involves inventing
+ -- a couple of new names which seems worse.
+ returnTc (TyLam sig_tyvars (HsLet (mk_binds inst_binds) arg'), free_insts)
)
where
-
- mk_binds []
- = EmptyBinds
- mk_binds ((inst,rhs):inst_binds)
- = (SingleBind (NonRecBind (VarMonoBind inst rhs)))
- `ThenBinds`
- mk_binds inst_binds
+ mk_binds inst_binds = MonoBind inst_binds [] nonRecursive
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcId :: Name -> TcM s (TcExpr s, LIE s, TcType s)
+tcId :: Name -> NF_TcM s (TcExpr s, LIE s, TcType s)
+
tcId name
= -- Look up the Id and instantiate its type
tcLookupLocalValue name `thenNF_Tc` \ maybe_local ->
- (case maybe_local of
- Just tc_id -> let
- (tyvars, rho) = splitForAllTy (idType tc_id)
- in
- tcInstTyVars tyvars `thenNF_Tc` \ (tyvars', arg_tys', tenv) ->
- tcInstTcType tenv rho `thenNF_Tc` \ rho' ->
- returnNF_Tc (TcId tc_id, arg_tys', rho')
-
- Nothing -> tcGlobalOcc name `thenNF_Tc` \ (id, arg_tys, rho) ->
- returnNF_Tc (RealId id, arg_tys, rho)
+ case maybe_local of
+ Just tc_id -> instantiate_it (TcId tc_id) (idType tc_id)
- ) `thenNF_Tc` \ (tc_id_occ, arg_tys, rho) ->
+ Nothing -> tcLookupGlobalValue name `thenNF_Tc` \ id ->
+ tcInstType [] (idType id) `thenNF_Tc` \ inst_ty ->
+ let
+ (tyvars, rho) = splitForAllTy inst_ty
+ in
+ instantiate_it2 (RealId id) tyvars rho
- -- Is it overloaded?
- case splitRhoTy rho of
- ([], tau) -> -- Not overloaded, so just make a type application
- returnTc (mkHsTyApp (HsVar tc_id_occ) arg_tys, emptyLIE, tau)
-
- (theta, tau) -> -- Overloaded, so make a Method inst
- newMethodWithGivenTy (OccurrenceOf tc_id_occ)
- tc_id_occ arg_tys rho `thenNF_Tc` \ (lie, meth_id) ->
- returnTc (HsVar meth_id, lie, 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 tc_id_occ ty
+ = tcInstTcType ty `thenNF_Tc` \ (tyvars, rho) ->
+ instantiate_it2 tc_id_occ tyvars rho
+
+ instantiate_it2 tc_id_occ tyvars rho
+ = tcSplitRhoTy rho `thenNF_Tc` \ (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 rho `thenNF_Tc` \ (lie1, meth_id) ->
+ instantiate_it meth_id tau `thenNF_Tc` \ (expr, lie2, final_tau) ->
+ returnNF_Tc (expr, lie1 `plusLIE` lie2, final_tau)
+
+ where
+ arg_tys = mkTyVarTys tyvars
\end{code}
-
-
%************************************************************************
%* *
-\subsection{@tcQuals@ typchecks list comprehension qualifiers}
+\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
%* *
%************************************************************************
\begin{code}
-tcListComp expr []
- = tcExpr expr `thenTc` \ (expr', lie, ty) ->
- returnTc ((expr',[]), lie, mkListTy ty)
-
-tcListComp expr (qual@(FilterQual filter) : quals)
- = tcAddErrCtxt (qualCtxt qual) (
- tcExpr filter `thenTc` \ (filter', filter_lie, filter_ty) ->
- unifyTauTy boolTy filter_ty `thenTc_`
- returnTc (FilterQual filter', filter_lie)
- ) `thenTc` \ (qual', qual_lie) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), rest_lie, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- qual_lie `plusLIE` rest_lie,
- res_ty)
-
-tcListComp expr (qual@(GeneratorQual pat rhs) : quals)
- = newMonoIds binder_names mkBoxedTypeKind (\ ids ->
-
- tcAddErrCtxt (qualCtxt qual) (
- tcPat pat `thenTc` \ (pat', lie_pat, pat_ty) ->
- tcExpr rhs `thenTc` \ (rhs', lie_rhs, rhs_ty) ->
- unifyTauTy (mkListTy pat_ty) rhs_ty `thenTc_`
- returnTc (GeneratorQual pat' rhs',
- lie_pat `plusLIE` lie_rhs)
- ) `thenTc` \ (qual', lie_qual) ->
-
- tcListComp expr quals `thenTc` \ ((expr',quals'), lie_rest, res_ty) ->
-
- returnTc ((expr', qual' : quals'),
- lie_qual `plusLIE` lie_rest,
- res_ty)
- )
- where
- binder_names = collectPatBinders pat
+tcDoStmts do_or_lc stmts src_loc
+ = -- get the Monad and MonadZero classes
+ -- create type consisting of a fresh monad tyvar
+ ASSERT( not (null stmts) )
+ tcAddSrcLoc src_loc $
+ newTyVarTy (mkArrowKind mkBoxedTypeKind mkBoxedTypeKind) `thenNF_Tc` \ m ->
-tcListComp expr (LetQual binds : quals)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (tcListComp expr quals)
- where
- combine binds' (expr',quals') = (expr', LetQual binds' : quals')
+ 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) ->
+
+ -- 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.
+ --
+ tcLookupGlobalValueByKey returnMClassOpKey `thenNF_Tc` \ return_sel_id ->
+ tcLookupGlobalValueByKey thenMClassOpKey `thenNF_Tc` \ then_sel_id ->
+ tcLookupGlobalValueByKey zeroClassOpKey `thenNF_Tc` \ zero_sel_id ->
+ newMethod DoOrigin
+ (RealId return_sel_id) [m] `thenNF_Tc` \ (return_lie, return_id) ->
+ newMethod DoOrigin
+ (RealId then_sel_id) [m] `thenNF_Tc` \ (then_lie, then_id) ->
+ newMethod DoOrigin
+ (RealId 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 result_ty src_loc,
+ final_lie `plusLIE` monad_lie,
+ result_ty)
\end{code}
+\begin{code}
+tcStmt :: (RenamedHsExpr -> TcM s (TcExpr s, LIE s, TcType 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 } )
+ tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
+ 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 } )
+ tcAddSrcLoc src_loc (
+ tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
+ unifyTauTy boolTy exp_ty `thenTc_`
+ 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 } )
+ tcAddSrcLoc src_loc (
+ tcSetErrCtxt (stmtCtxt do_or_lc stmt) (
+ tc_expr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
+ -- Check that exp has type (m tau) for some tau (doesn't matter what)
+ newTyVarTy mkTypeKind `thenNF_Tc` \ tau ->
+ unifyTauTy (m tau) exp_ty `thenTc_`
+ 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 `thenTc` \ (exp', exp_lie, exp_ty) ->
+ unifyTauTy (m pat_ty) exp_ty `thenTc_`
+
+ -- 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}
%************************************************************************
%* *
-\subsection{@tcDoStmts@ typechecks a {\em list} of do statements}
+\subsection{Record bindings}
%* *
%************************************************************************
-\begin{code}
-tcDoStmts :: Bool -- True => require a monad
- -> TcType s -- m
- -> [RenamedStmt]
- -> TcM s (([TcStmt s],
- Bool, -- True => Monad
- Bool), -- True => MonadZero
- LIE s,
- TcType s)
-
-tcDoStmts monad m [stmt@(ExprStmt exp src_loc)]
- = tcAddSrcLoc src_loc $
- tcSetErrCtxt (stmtCtxt stmt) $
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- (if monad then
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy (mkAppTy m a) exp_ty
- else
- returnTc ()
- ) `thenTc_`
- returnTc (([ExprStmt exp' src_loc], monad, False), exp_lie, exp_ty)
-
-tcDoStmts _ m (stmt@(ExprStmt exp src_loc) : stmts)
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy (mkAppTy m a) exp_ty `thenTc_`
- returnTc (ExprStmt exp' src_loc, exp_lie)
- )) `thenTc` \ (stmt', stmt_lie) ->
- tcDoStmts True m stmts `thenTc` \ ((stmts', _, mzero), stmts_lie, stmts_ty) ->
- returnTc ((stmt':stmts', True, mzero),
- stmt_lie `plusLIE` stmts_lie,
- stmts_ty)
-
-tcDoStmts _ m (stmt@(BindStmt pat exp src_loc) : stmts)
- = tcAddSrcLoc src_loc (
- tcSetErrCtxt (stmtCtxt stmt) (
- tcPat pat `thenTc` \ (pat', pat_lie, pat_ty) ->
- tcExpr exp `thenTc` \ (exp', exp_lie, exp_ty) ->
- newTyVarTy mkTypeKind `thenNF_Tc` \ a ->
- unifyTauTy a pat_ty `thenTc_`
- unifyTauTy (mkAppTy m a) exp_ty `thenTc_`
- returnTc (BindStmt pat' exp' src_loc, pat_lie `plusLIE` exp_lie, irrefutablePat pat')
- )) `thenTc` \ (stmt', stmt_lie, failure_free) ->
- tcDoStmts True m stmts `thenTc` \ ((stmts', _, mzero), stmts_lie, stmts_ty) ->
- returnTc ((stmt':stmts', True, mzero || not failure_free),
- stmt_lie `plusLIE` stmts_lie,
- stmts_ty)
-
-tcDoStmts monad m (LetStmt binds : stmts)
- = tcBindsAndThen -- No error context, but a binding group is
- combine -- rather a large thing for an error context anyway
- binds
- (tcDoStmts monad m stmts)
- where
- combine binds' (stmts', monad, mzero) = ((LetStmt binds' : stmts'), monad, mzero)
-
-\end{code}
-
Game plan for record bindings
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For each binding
returnTc (rbinds', plusLIEs lies)
where
do_bind (field_label, rhs, pun_flag)
- = tcGlobalOcc field_label `thenNF_Tc` \ (sel_id, _, tau) ->
+ = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
+ ASSERT( isRecordSelector sel_id )
+ -- This lookup and assertion will surely succeed, because
+ -- we check that the fields are indeed record selectors
+ -- before calling tcRecordBinds
+
+ tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
-- Record selectors all have type
-- forall a1..an. T a1 .. an -> tau
tcArg field_ty rhs `thenTc` \ (rhs', lie) ->
returnTc ((RealId sel_id, rhs', pun_flag), lie)
-checkRecordFields :: RenamedRecordBinds -> Id -> Bool -- True iff all the fields in
- -- RecordBinds are field of the
- -- specified constructor
-checkRecordFields rbinds data_con
- = all ok rbinds
- where
- data_con_fields = dataConFieldLabels data_con
-
- ok (field_name, _, _) = any (match field_name) data_con_fields
-
- match field_name field_label = field_name == fieldLabelName field_label
+badFields rbinds data_con
+ = [field_name | (field_name, _, _) <- rbinds,
+ not (field_name `elem` field_names)
+ ]
+ where
+ field_names = map fieldLabelName (dataConFieldLabels data_con)
\end{code}
%************************************************************************
Mini-utils:
\begin{code}
-pp_nest_hang :: String -> Pretty -> Pretty
-pp_nest_hang label stuff = ppNest 2 (ppHang (ppStr label) 4 stuff)
+pp_nest_hang :: String -> Doc -> Doc
+pp_nest_hang label stuff = nest 2 (hang (text label) 4 stuff)
\end{code}
Boring and alphabetical:
\begin{code}
arithSeqCtxt expr sty
- = ppHang (ppStr "In an arithmetic sequence:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr sty expr)
branchCtxt b1 b2 sty
- = ppSep [ppStr "In the branches of a conditional:",
+ = sep [ptext SLIT("In the branches of a conditional:"),
pp_nest_hang "`then' branch:" (ppr sty b1),
pp_nest_hang "`else' branch:" (ppr sty b2)]
caseCtxt expr sty
- = ppHang (ppStr "In a case expression:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In the case expression")) 4 (ppr sty expr)
exprSigCtxt expr sty
- = ppHang (ppStr "In an expression with a type signature:")
+ = hang (ptext SLIT("In an expression with a type signature:"))
4 (ppr sty expr)
listCtxt expr sty
- = ppHang (ppStr "In a list expression:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In the list element")) 4 (ppr sty expr)
predCtxt expr sty
- = ppHang (ppStr "In a predicate expression:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In the predicate expression")) 4 (ppr sty expr)
sectionRAppCtxt expr sty
- = ppHang (ppStr "In a right section:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In the right section")) 4 (ppr sty expr)
sectionLAppCtxt expr sty
- = ppHang (ppStr "In a left section:") 4 (ppr sty expr)
+ = hang (ptext SLIT("In the left section")) 4 (ppr sty expr)
funAppCtxt fun arg_no arg sty
- = ppHang (ppCat [ ppStr "In the", speakNth arg_no, ppStr "argument of", ppr sty fun])
- 4 (ppCat [ppStr "namely", ppr sty arg])
+ = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
+ ppr sty fun <> text ", namely"])
+ 4 (ppr sty arg)
-qualCtxt qual sty
- = ppHang (ppStr "In a list-comprehension qualifer:")
- 4 (ppr sty qual)
+stmtCtxt ListComp stmt sty
+ = hang (ptext SLIT("In a list-comprehension qualifer:"))
+ 4 (ppr sty stmt)
-stmtCtxt stmt sty
- = ppHang (ppStr "In a do statement:")
+stmtCtxt DoStmt stmt sty
+ = hang (ptext SLIT("In a do statement:"))
4 (ppr sty stmt)
tooManyArgsCtxt f sty
- = ppHang (ppStr "Too many arguments in an application of the function")
+ = hang (ptext SLIT("Too many arguments in an application of the function"))
4 (ppr sty f)
lurkingRank2Err fun fun_ty sty
- = ppHang (ppCat [ppStr "Illegal use of", ppr sty fun])
- 4 (ppAboves [ppStr "It is applied to too few arguments,",
- ppStr "so that the result type has for-alls in it"])
+ = hang (hsep [ptext SLIT("Illegal use of"), ppr sty fun])
+ 4 (vcat [text "It is applied to too few arguments,",
+ ptext SLIT("so that the result type has for-alls in it")])
rank2ArgCtxt arg expected_arg_ty sty
- = ppHang (ppStr "In a polymorphic function argument:")
- 4 (ppSep [ppBeside (ppr sty arg) (ppStr " ::"),
+ = hang (ptext SLIT("In a polymorphic function argument:"))
+ 4 (sep [(<>) (ppr sty arg) (ptext SLIT(" ::")),
ppr sty expected_arg_ty])
badFieldsUpd rbinds sty
- = ppHang (ppStr "In a record update construct, no constructor has all these fields:")
+ = hang (ptext SLIT("No constructor has all these fields:"))
4 (interpp'SP sty fields)
where
fields = [field | (field, _, _) <- rbinds]
-badFieldsCon con rbinds sty
- = ppHang (ppBesides [ppStr "Inconsistent constructor:", ppr sty con])
- 4 (ppBesides [ppStr "and fields:", interpp'SP sty fields])
- where
- fields = [field | (field, _, _) <- rbinds]
+recordUpdCtxt sty = ptext SLIT("In a record update construct")
+
+badFieldsCon con fields sty
+ = hsep [ptext SLIT("Constructor"), ppr sty con,
+ ptext SLIT("does not have field(s)"), interpp'SP sty fields]
+
+notSelector field sty
+ = hsep [ppr sty field, ptext SLIT("is not a record selector")]
\end{code}
projects / ghc-hetmet.git / blobdiff