%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-\section[TcExpr]{TcExpr}
+\section[TcExpr]{Typecheck an expression}
\begin{code}
+module TcExpr ( tcCheckSigma, tcCheckRho, tcInferRho, tcMonoExpr ) where
+
#include "HsVersions.h"
-module TcExpr (
- tcExpr
-#ifdef DPH
- , tcExprs
+#ifdef GHCI /* Only if bootstrapped */
+import {-# SOURCE #-} TcSplice( tcSpliceExpr, tcBracket )
+import Id ( Id )
+import TcType ( isTauTy )
+import TcEnv ( checkWellStaged )
+import HsSyn ( nlHsApp )
+import qualified DsMeta
#endif
- ) where
-import TcMonad -- typechecking monad machinery
-import TcMonadFns ( newPolyTyVarTy, newOpenTyVarTy,
- newDict, newMethod, newOverloadedLit,
- applyTcSubstAndCollectTyVars,
- mkIdsWithPolyTyVarTys
+import HsSyn ( HsExpr(..), LHsExpr, HsLit(..), ArithSeqInfo(..), recBindFields,
+ HsMatchContext(..), HsRecordBinds, mkHsApp, nlHsVar )
+import TcHsSyn ( hsLitType, mkHsDictApp, mkHsTyApp, (<$>) )
+import TcRnMonad
+import TcUnify ( Expected(..), newHole, zapExpectedType, zapExpectedTo, tcSubExp, tcGen,
+ unifyFunTy, zapToListTy, zapToPArrTy, zapToTupleTy )
+import BasicTypes ( isMarkedStrict )
+import Inst ( InstOrigin(..),
+ newOverloadedLit, newMethodFromName, newIPDict,
+ newDicts, newMethodWithGivenTy,
+ instToId, tcInstCall, tcInstDataCon
)
-import AbsSyn -- the stuff being typechecked
-
-
-import AbsPrel ( intPrimTy, charPrimTy, doublePrimTy,
- floatPrimTy, addrPrimTy, addrTy,
- boolTy, charTy, stringTy, mkFunTy, mkListTy,
- mkTupleTy, mkPrimIoTy
-#ifdef DPH
- ,mkProcessorTy, mkPodTy,toPodId,
- processorClass,pidClass
-#endif {- Data Parallel Haskell -}
+import TcBinds ( tcBindsAndThen )
+import TcEnv ( tcLookup, tcLookupId, checkProcLevel,
+ tcLookupDataCon, tcLookupGlobalId
)
-import AbsUniType
-import E
-import CE ( lookupCE )
-
-#ifndef DPH
-import Errors ( badMatchErr, UnifyErrContext(..) )
-#else
-import Errors ( badMatchErr, podCompLhsError, UnifyErrContext(..) )
-#endif {- Data Parallel Haskell -}
-
-import GenSpecEtc ( checkSigTyVars )
-import Id ( mkInstId, getIdUniType, Id )
-import Inst
-import LIE ( nullLIE, unitLIE, plusLIE, unMkLIE, mkLIE, LIE )
-import ListSetOps ( unionLists )
-import Maybes ( Maybe(..) )
-import TVE ( nullTVE, TVE(..) )
-import Spec ( specId, specTy )
-import TcBinds ( tcLocalBindsAndThen )
-import TcMatches ( tcMatchesCase, tcMatch )
-import TcPolyType ( tcPolyType )
-import TcQuals ( tcQuals )
-import TcSimplify ( tcSimplifyAndCheck, tcSimplifyRank2 )
-#ifdef DPH
-import TcParQuals
-#endif {- Data Parallel Haskell -}
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists )
-import UniqFM ( emptyUFM ) -- profiling, pragmas only
-import Unique -- *Key stuff
+import TcArrows ( tcProc )
+import TcMatches ( tcMatchesCase, tcMatchLambda, tcDoStmts, tcThingWithSig, TcMatchCtxt(..) )
+import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
+import TcPat ( badFieldCon )
+import TcMType ( tcInstTyVars, tcInstType, newTyVarTy, zonkTcType )
+import TcType ( TcType, TcSigmaType, TcRhoType, TyVarDetails(VanillaTv),
+ tcSplitFunTys, tcSplitTyConApp, mkTyVarTys,
+ isSigmaTy, mkFunTy, mkFunTys,
+ mkTyConApp, tyVarsOfTypes, isLinearPred,
+ tcSplitSigmaTy, tidyOpenType
+ )
+import Kind ( openTypeKind, liftedTypeKind, argTypeKind )
+
+import FieldLabel ( FieldLabel, fieldLabelName, fieldLabelType, fieldLabelTyCon )
+import Id ( idType, recordSelectorFieldLabel, isRecordSelector )
+import DataCon ( DataCon, dataConFieldLabels, dataConStrictMarks, dataConWrapId )
+import Name ( Name )
+import TyCon ( TyCon, tyConTyVars, tyConTheta, tyConDataCons )
+import Subst ( mkTopTyVarSubst, substTheta, substTy )
+import VarSet ( emptyVarSet, elemVarSet )
+import TysWiredIn ( boolTy )
+import PrelNames ( enumFromName, enumFromThenName,
+ enumFromToName, enumFromThenToName,
+ enumFromToPName, enumFromThenToPName
+ )
+import ListSetOps ( minusList )
+import CmdLineOpts
+import HscTypes ( TyThing(..) )
+import SrcLoc ( Located(..), unLoc, getLoc )
import Util
+import Outputable
+import FastString
-tcExpr :: E -> RenamedExpr -> TcM (TypecheckedExpr, LIE, UniType)
+#ifdef DEBUG
+import TyCon ( isAlgTyCon )
+#endif
\end{code}
%************************************************************************
%* *
-\subsection{The TAUT rules for variables}
+\subsection{Main wrappers}
%* *
%************************************************************************
\begin{code}
-tcExpr e (Var name)
- = specId (lookupE_Value e name) `thenNF_Tc` \ stuff@(expr, lie, ty) ->
+-- tcCheckSigma does type *checking*; it's passed the expected type of the result
+tcCheckSigma :: LHsExpr Name -- Expession to type check
+ -> TcSigmaType -- Expected type (could be a polytpye)
+ -> TcM (LHsExpr TcId) -- Generalised expr with expected type
+
+tcCheckSigma expr expected_ty
+ = traceTc (text "tcExpr" <+> (ppr expected_ty $$ ppr expr)) `thenM_`
+ tc_expr' expr expected_ty
+
+tc_expr' expr sigma_ty
+ | isSigmaTy sigma_ty
+ = tcGen sigma_ty emptyVarSet (
+ \ rho_ty -> tcCheckRho expr rho_ty
+ ) `thenM` \ (gen_fn, expr') ->
+ returnM (L (getLoc expr') (gen_fn <$> unLoc expr'))
+
+tc_expr' expr rho_ty -- Monomorphic case
+ = tcCheckRho expr rho_ty
+\end{code}
- -- Check that there's no lurking rank-2 polymorphism
- -- isTauTy is over-paranoid, because we don't expect
- -- any submerged polymorphism other than rank-2 polymorphism
+Typecheck expression which in most cases will be an Id.
+The expression can return a higher-ranked type, such as
+ (forall a. a->a) -> Int
+so we must create a hole to pass in as the expected tyvar.
- checkTc (not (isTauTy ty)) (error "tcExpr Var: MISSING ERROR MESSAGE") -- ToDo:
- `thenTc_`
-
- returnTc stuff
+\begin{code}
+tcCheckRho :: LHsExpr Name -> TcRhoType -> TcM (LHsExpr TcId)
+tcCheckRho expr rho_ty = tcMonoExpr expr (Check rho_ty)
+
+tcInferRho :: LHsExpr Name -> TcM (LHsExpr TcId, TcRhoType)
+tcInferRho (L loc (HsVar name)) = addSrcSpan loc $
+ do { (e,ty) <- tcId name; return (L loc e, ty)}
+tcInferRho expr = newHole `thenM` \ hole ->
+ tcMonoExpr expr (Infer hole) `thenM` \ expr' ->
+ readMutVar hole `thenM` \ rho_ty ->
+ returnM (expr', rho_ty)
\end{code}
+
+
%************************************************************************
%* *
-\subsection{Literals}
+\subsection{The TAUT rules for variables}TcExpr
%* *
%************************************************************************
-Overloaded literals.
-
\begin{code}
-tcExpr e (Lit lit@(IntLit i))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- newPolyTyVarTy `thenNF_Tc` \ ty ->
- let
- from_int = lookupE_ClassOpByKey e numClassKey SLIT("fromInt")
- from_integer = lookupE_ClassOpByKey e numClassKey SLIT("fromInteger")
- in
- newOverloadedLit (LiteralOrigin lit loc)
- (OverloadedIntegral i from_int from_integer)
- ty
- `thenNF_Tc` \ over_lit ->
-
- returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty)
-
-tcExpr e (Lit lit@(FracLit f))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- newPolyTyVarTy `thenNF_Tc` \ ty ->
- let
- from_rational = lookupE_ClassOpByKey e fractionalClassKey SLIT("fromRational")
- in
- newOverloadedLit (LiteralOrigin lit loc)
- (OverloadedFractional f from_rational)
- ty
- `thenNF_Tc` \ over_lit ->
-
- returnTc (Var (mkInstId over_lit), unitLIE over_lit, ty)
-
-tcExpr e (Lit lit@(LitLitLitIn s))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- let
- -- Get the callable class. Rather turgid and a HACK (ToDo).
- ce = getE_CE e
- cCallableClass = lookupCE ce (PreludeClass cCallableClassKey bottom)
- bottom = panic "tcExpr:LitLitLit"
- in
- newPolyTyVarTy `thenNF_Tc` \ ty ->
-
- newDict (LitLitOrigin loc (_UNPK_ s)) cCallableClass ty `thenNF_Tc` \ dict ->
-
- returnTc (Lit (LitLitLit s ty), mkLIE [dict], ty)
+tcMonoExpr :: LHsExpr Name -- Expession to type check
+ -> Expected TcRhoType -- Expected type (could be a type variable)
+ -- Definitely no foralls at the top
+ -- Can be a 'hole'.
+ -> TcM (LHsExpr TcId)
+
+tcMonoExpr (L loc expr) res_ty
+ = addSrcSpan loc (do { expr' <- tc_expr expr res_ty
+ ; return (L loc expr') })
+
+tc_expr :: HsExpr Name -> Expected TcRhoType -> TcM (HsExpr TcId)
+tc_expr (HsVar name) res_ty
+ = tcId name `thenM` \ (expr', id_ty) ->
+ tcSubExp res_ty id_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> expr')
+
+tc_expr (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 argTypeKind `thenM` \ ip_ty ->
+ -- argTypeKind: it can't be an unboxed tuple
+ newIPDict (IPOccOrigin ip) ip ip_ty `thenM` \ (ip', inst) ->
+ extendLIE inst `thenM_`
+ tcSubExp res_ty ip_ty `thenM` \ co_fn ->
+ returnM (co_fn <$> HsIPVar ip')
\end{code}
-Primitive literals:
-
-\begin{code}
-tcExpr e (Lit (CharPrimLit c))
- = returnTc (Lit (CharPrimLit c), nullLIE, charPrimTy)
-
-tcExpr e (Lit (StringPrimLit s))
- = returnTc (Lit (StringPrimLit s), nullLIE, addrPrimTy)
-
-tcExpr e (Lit (IntPrimLit i))
- = returnTc (Lit (IntPrimLit i), nullLIE, intPrimTy)
-
-tcExpr e (Lit (FloatPrimLit f))
- = returnTc (Lit (FloatPrimLit f), nullLIE, floatPrimTy)
-
-tcExpr e (Lit (DoublePrimLit d))
- = returnTc (Lit (DoublePrimLit d), nullLIE, doublePrimTy)
-\end{code}
-Unoverloaded literals:
+%************************************************************************
+%* *
+\subsection{Expressions type signatures}
+%* *
+%************************************************************************
\begin{code}
-tcExpr e (Lit (CharLit c))
- = returnTc (Lit (CharLit c), nullLIE, charTy)
-
-tcExpr e (Lit (StringLit str))
- = returnTc (Lit (StringLit str), nullLIE, stringTy)
+tc_expr in_expr@(ExprWithTySig expr poly_ty) res_ty
+ = addErrCtxt (exprCtxt in_expr) $
+ tcHsSigType ExprSigCtxt poly_ty `thenM` \ sig_tc_ty ->
+ tcThingWithSig sig_tc_ty (tcCheckRho expr) res_ty `thenM` \ (co_fn, expr') ->
+ returnM (co_fn <$> unLoc expr')
+ -- ToDo: nasty unLoc
+
+tc_expr (HsType ty) res_ty
+ = failWithTc (text "Can't handle type argument:" <+> ppr ty)
+ -- This is the syntax for type applications that I was planning
+ -- but there are difficulties (e.g. what order for type args)
+ -- so it's not enabled yet.
+ -- Can't eliminate it altogether from the parser, because the
+ -- same parser parses *patterns*.
\end{code}
+
%************************************************************************
%* *
\subsection{Other expression forms}
%************************************************************************
\begin{code}
-tcExpr e (Lam match)
- = tcMatch e match `thenTc` \ (match',lie,ty) ->
- returnTc (Lam match',lie,ty)
-
-tcExpr e (App e1 e2) = accum e1 [e2]
- where
- accum (App e1 e2) args = accum e1 (e2:args)
- accum fun args = tcApp (foldl App) e fun args
-
--- equivalent to (op e1) e2:
-tcExpr e (OpApp e1 op e2)
- = tcApp (\fun [arg1,arg2] -> OpApp arg1 fun arg2) e op [e1,e2]
+tc_expr (HsPar expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsPar expr')
+tc_expr (HsSCC lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' ->
+ returnM (HsSCC lbl expr')
+tc_expr (HsCoreAnn lbl expr) res_ty = tcMonoExpr expr res_ty `thenM` \ expr' -> -- hdaume: core annotation
+ returnM (HsCoreAnn lbl expr')
+
+tc_expr (HsLit lit) res_ty = tcLit lit res_ty
+
+tc_expr (HsOverLit lit) res_ty
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ newOverloadedLit (LiteralOrigin lit) lit res_ty' `thenM` \ lit_expr ->
+ returnM (unLoc lit_expr) -- ToDo: nasty unLoc
+
+tc_expr (NegApp expr neg_name) res_ty
+ = tc_expr (HsApp (nlHsVar neg_name) expr) res_ty
+ -- ToDo: use tcSyntaxName
+
+tc_expr (HsLam match) res_ty
+ = tcMatchLambda match res_ty `thenM` \ match' ->
+ returnM (HsLam match')
+
+tc_expr (HsApp e1 e2) res_ty
+ = tcApp e1 [e2] res_ty
\end{code}
Note that the operators in sections are expected to be binary, and
a type error will occur if they aren't.
\begin{code}
--- equivalent to
--- \ x -> e op x,
+-- Left sections, equivalent to
+-- \ x -> e op x,
-- or
--- \ x -> op e x,
+-- \ x -> op e x,
-- or just
-- op e
-tcExpr e (SectionL expr op)
- = tcApp (\ fun [arg] -> SectionL arg fun) e op [expr]
+tc_expr in_expr@(SectionL arg1 op) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty (mkFunTy arg2_ty op_res_ty) `thenM` \ co_fn ->
+ returnM (co_fn <$> SectionL arg1' op')
--- equivalent to \ x -> x op expr, or
+-- Right sections, equivalent to \ x -> x op expr, or
-- \ x -> op x expr
-tcExpr e (SectionR op expr)
- = tcExpr e op `thenTc` \ (op', lie1, op_ty) ->
- tcExpr e expr `thenTc` \ (expr',lie2, expr_ty) ->
- newOpenTyVarTy `thenNF_Tc` \ ty1 ->
- newOpenTyVarTy `thenNF_Tc` \ ty2 ->
- let
- result_ty = mkFunTy ty1 ty2
- in
- unifyTauTy op_ty (mkFunTy ty1 (mkFunTy expr_ty ty2))
- (SectionRAppCtxt op expr) `thenTc_`
-
- returnTc (SectionR op' expr', plusLIE lie1 lie2, result_ty)
-\end{code}
-
-The interesting thing about @ccall@ is that it is just a template
-which we instantiate by filling in details about the types of its
-argument and result (ie minimal typechecking is performed). So, the
-basic story is that we allocate a load of type variables (to hold the
-arg/result types); unify them with the args/result; and store them for
-later use.
+tc_expr in_expr@(SectionR op arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty (mkFunTy arg1_ty op_res_ty) `thenM` \ co_fn ->
+ returnM (co_fn <$> SectionR op' arg2')
-\begin{code}
-tcExpr e (CCall lbl args may_gc is_asm ignored_fake_result_ty)
- = getSrcLocTc `thenNF_Tc` \ src_loc ->
- let
- -- Get the callable and returnable classes. Rather turgid (ToDo).
- ce = getE_CE e
- cCallableClass = lookupCE ce (PreludeClass cCallableClassKey bottom)
- cReturnableClass = lookupCE ce (PreludeClass cReturnableClassKey bottom)
- bottom = panic "tcExpr:CCall"
-
- new_arg_dict (arg, arg_ty) = newDict (CCallOrigin src_loc (_UNPK_ lbl) (Just arg))
- cCallableClass arg_ty
+-- equivalent to (op e1) e2:
- result_origin = CCallOrigin src_loc (_UNPK_ lbl) Nothing {- Not an arg -}
- in
-
- -- Arguments
- tcExprs e args `thenTc` \ (args', args_lie, arg_tys) ->
-
- -- The argument types can be unboxed or boxed; the result
- -- type must, however, be boxed since it's an argument to the PrimIO
- -- type constructor.
- newPolyTyVarTy `thenNF_Tc` \ result_ty ->
-
- -- 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` \ arg_dicts ->
- newDict result_origin cReturnableClass result_ty `thenNF_Tc` \ res_dict ->
-
- returnTc (CCall lbl args' may_gc is_asm result_ty,
- args_lie `plusLIE` mkLIE (res_dict : arg_dicts),
- mkPrimIoTy result_ty)
+tc_expr in_expr@(OpApp arg1 op fix arg2) res_ty
+ = tcInferRho op `thenM` \ (op', op_ty) ->
+ split_fun_ty op_ty 2 {- two args -} `thenM` \ ([arg1_ty, arg2_ty], op_res_ty) ->
+ tcArg op (arg1, arg1_ty, 1) `thenM` \ arg1' ->
+ tcArg op (arg2, arg2_ty, 2) `thenM` \ arg2' ->
+ addErrCtxt (exprCtxt in_expr) $
+ tcSubExp res_ty op_res_ty `thenM` \ co_fn ->
+ returnM (OpApp arg1' op' fix arg2')
\end{code}
\begin{code}
-tcExpr e (SCC label expr)
- = tcExpr e expr `thenTc` \ (expr', lie, expr_ty) ->
- -- No unification. Give SCC the type of expr
- returnTc (SCC label expr', lie, expr_ty)
-
-tcExpr e (Let binds expr)
- = tcLocalBindsAndThen e
- Let -- The combiner
- binds -- Bindings to check
- (\ e -> tcExpr e expr) -- Typechecker for the expression
-
-tcExpr e (Case expr matches)
- = tcExpr e expr `thenTc` \ (expr',lie1,expr_ty) ->
- tcMatchesCase e matches `thenTc` \ (matches',lie2,match_ty) ->
- newOpenTyVarTy `thenNF_Tc` \ result_ty ->
-
- unifyTauTy (mkFunTy expr_ty result_ty) match_ty
- (CaseCtxt expr matches) `thenTc_`
-
- returnTc (Case expr' matches', plusLIE lie1 lie2, result_ty)
-
-tcExpr e (If pred b1 b2)
- = tcExpr e pred `thenTc` \ (pred',lie1,predTy) ->
+tc_expr (HsLet binds (L loc expr)) res_ty
+ = tcBindsAndThen
+ glue
+ binds -- Bindings to check
+ (tc_expr expr res_ty)
+ where
+ glue bind expr = HsLet [bind] (L loc expr)
- unifyTauTy predTy boolTy (PredCtxt pred) `thenTc_`
+tc_expr in_expr@(HsCase scrut matches) res_ty
+ = addErrCtxt (caseCtxt in_expr) $
- tcExpr e b1 `thenTc` \ (b1',lie2,result_ty) ->
- tcExpr e b2 `thenTc` \ (b2',lie3,b2Ty) ->
+ -- Typecheck the case alternatives first.
+ -- The case patterns tend to give good type info to use
+ -- when typechecking the scrutinee. For example
+ -- case (map f) of
+ -- (x:xs) -> ...
+ -- will report that map is applied to too few arguments
- unifyTauTy result_ty b2Ty (BranchCtxt b1 b2) `thenTc_`
+ tcMatchesCase match_ctxt matches res_ty `thenM` \ (scrut_ty, matches') ->
- returnTc (If pred' b1' b2', plusLIE lie1 (plusLIE lie2 lie3), result_ty)
+ addErrCtxt (caseScrutCtxt scrut) (
+ tcCheckRho scrut scrut_ty
+ ) `thenM` \ scrut' ->
-tcExpr e (ListComp expr quals)
- = mkIdsWithPolyTyVarTys binders `thenNF_Tc` \ lve ->
- -- Binders of a list comprehension must be boxed.
- let
- new_e = growE_LVE e lve
- in
- tcQuals new_e quals `thenTc` \ (quals',lie1) ->
- tcExpr new_e expr `thenTc` \ (expr', lie2, ty) ->
- returnTc (ListComp expr' quals', plusLIE lie1 lie2, mkListTy ty)
+ returnM (HsCase scrut' matches')
+ where
+ match_ctxt = MC { mc_what = CaseAlt,
+ mc_body = tcMonoExpr }
+
+tc_expr (HsIf pred b1 b2) res_ty
+ = addErrCtxt (predCtxt pred) (
+ tcCheckRho pred boolTy ) `thenM` \ pred' ->
+
+ zapExpectedType res_ty openTypeKind `thenM` \ res_ty' ->
+ -- C.f. the call to zapToType in TcMatches.tcMatches
+
+ tcCheckRho b1 res_ty' `thenM` \ b1' ->
+ tcCheckRho b2 res_ty' `thenM` \ b2' ->
+ returnM (HsIf pred' b1' b2')
+
+tc_expr (HsDo do_or_lc stmts method_names _) res_ty
+ = zapExpectedType res_ty liftedTypeKind `thenM` \ res_ty' ->
+ -- All comprehensions yield a monotype of kind *
+ tcDoStmts do_or_lc stmts method_names res_ty' `thenM` \ (stmts', methods') ->
+ returnM (HsDo do_or_lc stmts' methods' res_ty')
+
+tc_expr in_expr@(ExplicitList _ exprs) res_ty -- Non-empty list
+ = zapToListTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitList elt_ty exprs')
+ where
+ tc_elt elt_ty expr
+ = addErrCtxt (listCtxt expr) $
+ tcCheckRho expr elt_ty
+
+tc_expr in_expr@(ExplicitPArr _ exprs) res_ty -- maybe empty
+ = zapToPArrTy res_ty `thenM` \ elt_ty ->
+ mappM (tc_elt elt_ty) exprs `thenM` \ exprs' ->
+ returnM (ExplicitPArr elt_ty exprs')
where
- binders = collectQualBinders quals
+ tc_elt elt_ty expr
+ = addErrCtxt (parrCtxt expr) $
+ tcCheckRho expr elt_ty
+
+tc_expr (ExplicitTuple exprs boxity) res_ty
+ = zapToTupleTy boxity (length exprs) res_ty `thenM` \ arg_tys ->
+ tcCheckRhos exprs arg_tys `thenM` \ exprs' ->
+ returnM (ExplicitTuple exprs' boxity)
+
+tc_expr (HsProc pat cmd) res_ty
+ = tcProc pat cmd res_ty `thenM` \ (pat', cmd') ->
+ returnM (HsProc pat' cmd')
\end{code}
-\begin{code}
-tcExpr e (ExplicitList [])
- = newPolyTyVarTy `thenNF_Tc` \ tyvar_ty ->
- returnTc (ExplicitListOut tyvar_ty [], nullLIE, mkListTy tyvar_ty)
-
-
-tcExpr e (ExplicitList exprs) -- Non-empty list
- = tcExprs e exprs `thenTc` \ (exprs', lie, tys@(elt_ty:_)) ->
- unifyTauTyList tys (ListCtxt exprs) `thenTc_`
- returnTc (ExplicitListOut elt_ty exprs', lie, mkListTy elt_ty)
-
-tcExpr e (ExplicitTuple exprs)
- = tcExprs e exprs `thenTc` \ (exprs', lie, tys) ->
- returnTc (ExplicitTuple exprs', lie, mkTupleTy (length tys) tys)
+%************************************************************************
+%* *
+ Record construction and update
+%* *
+%************************************************************************
-tcExpr e (ArithSeqIn seq@(From expr))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- tcExpr e expr `thenTc` \ (expr', lie, ty) ->
+\begin{code}
+tc_expr expr@(RecordCon con@(L _ con_name) rbinds) res_ty
+ = addErrCtxt (recordConCtxt expr) $
+ addLocM tcId con `thenM` \ (con_expr, con_tau) ->
let
- enum_from_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFrom")
+ (_, record_ty) = tcSplitFunTys con_tau
+ (tycon, ty_args) = tcSplitTyConApp record_ty
in
- newMethod (ArithSeqOrigin seq loc)
- enum_from_id [ty] `thenNF_Tc` \ enum_from ->
-
- returnTc (ArithSeqOut (Var (mkInstId enum_from)) (From expr'),
- plusLIE (unitLIE enum_from) lie,
- mkListTy ty)
+ ASSERT( isAlgTyCon tycon )
+ zapExpectedTo res_ty record_ty `thenM_`
-tcExpr e (ArithSeqIn seq@(FromThen expr1 expr2))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) ->
+ -- Check that the record bindings match the constructor
+ -- con_name is syntactically constrained to be a data constructor
+ tcLookupDataCon con_name `thenM` \ data_con ->
+ let
+ bad_fields = badFields rbinds data_con
+ in
+ if notNull bad_fields then
+ mappM (addErrTc . badFieldCon data_con) bad_fields `thenM_`
+ failM -- Fail now, because tcRecordBinds will crash on a bad field
+ else
- unifyTauTyList [ty1, ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_`
+ -- Typecheck the record bindings
+ tcRecordBinds tycon ty_args rbinds `thenM` \ rbinds' ->
+
+ -- Check for missing fields
+ checkMissingFields data_con rbinds `thenM_`
+
+ getSrcSpanM `thenM` \ loc ->
+ returnM (RecordConOut data_con (L loc con_expr) rbinds')
+
+-- 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.
+
+tc_expr expr@(RecordUpd record_expr rbinds) res_ty
+ = addErrCtxt (recordUpdCtxt expr) $
+
+ -- STEP 0
+ -- Check that the field names are really field names
+ ASSERT( notNull rbinds )
+ let
+ field_names = map fst rbinds
+ in
+ mappM (tcLookupGlobalId.unLoc) field_names `thenM` \ sel_ids ->
+ -- The renamer has already checked that they
+ -- are all in scope
+ let
+ bad_guys = [ addSrcSpan loc $ addErrTc (notSelector field_name)
+ | (L loc field_name, sel_id) <- field_names `zip` sel_ids,
+ not (isRecordSelector sel_id) -- Excludes class ops
+ ]
+ in
+ checkM (null bad_guys) (sequenceM bad_guys `thenM_` failM) `thenM_`
+
+ -- STEP 1
+ -- Figure out the tycon and data cons from the first field name
+ let
+ -- It's OK to use the non-tc splitters here (for a selector)
+ sel_id : _ = sel_ids
+ field_lbl = recordSelectorFieldLabel sel_id -- We've failed already if
+ tycon = fieldLabelTyCon field_lbl -- it's not a field label
+ data_cons = tyConDataCons tycon
+ tycon_tyvars = tyConTyVars tycon -- The data cons use the same type vars
+ in
+ tcInstTyVars VanillaTv tycon_tyvars `thenM` \ (_, result_inst_tys, inst_env) ->
+
+ -- STEP 2
+ -- Check that at least one constructor has all the named fields
+ -- i.e. has an empty set of bad fields returned by badFields
+ checkTc (any (null . badFields rbinds) data_cons)
+ (badFieldsUpd rbinds) `thenM_`
+
+ -- 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
- enum_from_then_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThen")
+ result_record_ty = mkTyConApp tycon result_inst_tys
in
- newMethod (ArithSeqOrigin seq loc)
- enum_from_then_id [ty1] `thenNF_Tc` \ enum_from_then ->
+ zapExpectedTo res_ty result_record_ty `thenM_`
+ tcRecordBinds tycon result_inst_tys rbinds `thenM` \ rbinds' ->
+
+ -- STEP 4
+ -- Use the un-updated fields to find a vector of booleans saying
+ -- 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 = map recordSelectorFieldLabel (recBindFields rbinds')
+ con_field_lbls_s = map dataConFieldLabels data_cons
- returnTc (ArithSeqOut (Var (mkInstId enum_from_then))
- (FromThen expr1' expr2'),
- (unitLIE enum_from_then) `plusLIE` lie1 `plusLIE` lie2,
- mkListTy ty1)
+ -- 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
-tcExpr e (ArithSeqIn seq@(FromTo expr1 expr2))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) ->
+ non_upd_field_lbls = concat relevant_field_lbls_s `minusList` upd_field_lbls
+ common_tyvars = tyVarsOfTypes (map fieldLabelType non_upd_field_lbls)
- unifyTauTyList [ty1,ty2] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_`
+ mk_inst_ty (tyvar, result_inst_ty)
+ | tyvar `elemVarSet` common_tyvars = returnM result_inst_ty -- Same as result type
+ | otherwise = newTyVarTy liftedTypeKind -- Fresh type
+ in
+ mappM mk_inst_ty (zip tycon_tyvars result_inst_tys) `thenM` \ inst_tys ->
+
+ -- STEP 5
+ -- Typecheck the expression to be updated
let
- enum_from_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromTo")
+ record_ty = mkTyConApp tycon inst_tys
in
- newMethod (ArithSeqOrigin seq loc)
- enum_from_to_id [ty1] `thenNF_Tc` \ enum_from_to ->
- returnTc (ArithSeqOut (Var (mkInstId enum_from_to))
- (FromTo expr1' expr2'),
- (unitLIE enum_from_to) `plusLIE` lie1 `plusLIE` lie2,
- mkListTy ty1)
-
-tcExpr e (ArithSeqIn seq@(FromThenTo expr1 expr2 expr3))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- tcExpr e expr1 `thenTc` \ (expr1',lie1,ty1) ->
- tcExpr e expr2 `thenTc` \ (expr2',lie2,ty2) ->
- tcExpr e expr3 `thenTc` \ (expr3',lie3,ty3) ->
-
- unifyTauTyList [ty1,ty2,ty3] (ArithSeqCtxt (ArithSeqIn seq)) `thenTc_`
+ tcCheckRho record_expr record_ty `thenM` \ record_expr' ->
+
+ -- STEP 6
+ -- Figure out the LIE we need. We have to generate some
+ -- dictionaries for the data type context, since we are going to
+ -- do pattern matching over the data cons.
+ --
+ -- What dictionaries do we need?
+ -- We just take the context of the type constructor
let
- enum_from_then_to_id = lookupE_ClassOpByKey e enumClassKey SLIT("enumFromThenTo")
+ theta' = substTheta inst_env (tyConTheta tycon)
in
- newMethod (ArithSeqOrigin seq loc)
- enum_from_then_to_id [ty1] `thenNF_Tc` \ enum_from_then_to ->
+ newDicts RecordUpdOrigin theta' `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
- returnTc (ArithSeqOut (Var (mkInstId enum_from_then_to))
- (FromThenTo expr1' expr2' expr3'),
- (unitLIE enum_from_then_to) `plusLIE` lie1 `plusLIE` lie2 `plusLIE` lie3,
- mkListTy ty1)
+ -- Phew!
+ returnM (RecordUpdOut record_expr' record_ty result_record_ty rbinds')
\end{code}
+
%************************************************************************
%* *
-\subsection{Expressions type signatures}
+ Arithmetic sequences e.g. [a,b..]
+ and their parallel-array counterparts e.g. [: a,b.. :]
+
%* *
%************************************************************************
\begin{code}
-tcExpr e (ExprWithTySig expr poly_ty)
- = tcExpr e expr `thenTc` \ (texpr, lie, tau_ty) ->
- babyTcMtoTcM (tcPolyType (getE_CE e) (getE_TCE e) nullTVE poly_ty) `thenTc` \ sigma_sig ->
-
- -- Check the tau-type part
- specTy SignatureOrigin sigma_sig `thenNF_Tc` \ (sig_tyvars, sig_dicts, sig_tau) ->
- unifyTauTy tau_ty sig_tau (ExprSigCtxt expr sig_tau) `thenTc_`
-
- -- Check the type variables of the signature
- applyTcSubstAndCollectTyVars (tvOfE e) `thenNF_Tc` \ env_tyvars ->
- checkSigTyVars env_tyvars sig_tyvars sig_tau tau_ty (ExprSigCtxt expr sig_tau)
- `thenTc` \ sig_tyvars' ->
-
- -- Check overloading constraints
- tcSimplifyAndCheck
- False {- Not top level -}
- env_tyvars sig_tyvars'
- sig_dicts (unMkLIE lie)
- (ExprSigCtxt expr sigma_sig) `thenTc_`
-
- -- If everything is ok, return the stuff unchanged, except for
- -- the effect of any substutions etc. We simply discard the
- -- result of the tcSimplifyAndCheck, except for any default
- -- resolution it may have done, which is recorded in the
- -- substitution.
- returnTc (texpr, lie, tau_ty)
+tc_expr (ArithSeqIn seq@(From expr)) res_ty
+ = zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr elt_ty `thenM` \ expr' ->
+
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromName `thenM` \ enum_from ->
+
+ returnM (ArithSeqOut (nlHsVar enum_from) (From expr'))
+
+tc_expr in_expr@(ArithSeqIn seq@(FromThen expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenName `thenM` \ enum_from_then ->
+
+ returnM (ArithSeqOut (nlHsVar enum_from_then) (FromThen expr1' expr2'))
+
+
+tc_expr in_expr@(ArithSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromToName `thenM` \ enum_from_to ->
+
+ returnM (ArithSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+
+tc_expr in_expr@(ArithSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (arithSeqCtxt in_expr) $
+ zapToListTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (ArithSeqOrigin seq)
+ elt_ty enumFromThenToName `thenM` \ eft ->
+
+ returnM (ArithSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+tc_expr in_expr@(PArrSeqIn seq@(FromTo expr1 expr2)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToPArrTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromToPName `thenM` \ enum_from_to ->
+
+ returnM (PArrSeqOut (nlHsVar enum_from_to) (FromTo expr1' expr2'))
+
+tc_expr in_expr@(PArrSeqIn seq@(FromThenTo expr1 expr2 expr3)) res_ty
+ = addErrCtxt (parrSeqCtxt in_expr) $
+ zapToPArrTy res_ty `thenM` \ elt_ty ->
+ tcCheckRho expr1 elt_ty `thenM` \ expr1' ->
+ tcCheckRho expr2 elt_ty `thenM` \ expr2' ->
+ tcCheckRho expr3 elt_ty `thenM` \ expr3' ->
+ newMethodFromName (PArrSeqOrigin seq)
+ elt_ty enumFromThenToPName `thenM` \ eft ->
+
+ returnM (PArrSeqOut (nlHsVar eft) (FromThenTo expr1' expr2' expr3'))
+
+tc_expr (PArrSeqIn _) _
+ = panic "TcExpr.tcMonoExpr: Infinite parallel array!"
+ -- the parser shouldn't have generated it and the renamer shouldn't have
+ -- let it through
\end{code}
+
%************************************************************************
%* *
-\subsection{Data Parallel Expressions (DPH only)}
+ Template Haskell
%* *
%************************************************************************
-Constraints enforced by the Static semantics for ParallelZF
-$exp_1$ = << $exp_2$ | quals >>
+\begin{code}
+#ifdef GHCI /* Only if bootstrapped */
+ -- Rename excludes these cases otherwise
+tc_expr (HsSpliceE splice) res_ty = tcSpliceExpr splice res_ty
+tc_expr (HsBracket brack) res_ty = do { e <- tcBracket brack res_ty
+ ; return (unLoc e) }
+#endif /* GHCI */
+\end{code}
-\begin{enumerate}
-\item The type of the expression $exp_1$ is <<$exp_2$>>
-\item The type of $exp_2$ must be in the class {\tt Processor}
-\end{enumerate}
+
+%************************************************************************
+%* *
+ Catch-all
+%* *
+%************************************************************************
\begin{code}
-#ifdef DPH
-tcExpr e (ParallelZF expr quals)
- = let binders = collectParQualBinders quals in
- mkIdsWithPolyTyVarTys binders `thenNF_Tc` (\ lve ->
- let e' = growE_LVE e lve in
- tcParQuals e' quals `thenTc` (\ (quals',lie1) ->
- tcExpr e' expr `thenTc` (\ (expr', lie2,ty) ->
- getSrcLocTc `thenNF_Tc` (\ src_loc ->
- if (isProcessorTy ty) then
- returnTc (ParallelZF expr' quals',
- plusLIE lie1 lie2 ,
- mkPodTy ty)
- else
- failTc (podCompLhsError ty src_loc)
- ))))
-#endif {- Data Parallel Haskell -}
+tc_expr other _ = pprPanic "tcMonoExpr" (ppr other)
\end{code}
-Constraints enforced by the Static semantics for Explicit Pods
-exp = << $exp_1$ ... $exp_n$>> (where $n >= 0$)
-\begin{enumerate}
-\item The type of the all the expressions in the Pod must be the same.
-\item The type of an expression in a POD must be in class {\tt Processor}
-\end{enumerate}
+%************************************************************************
+%* *
+\subsection{@tcApp@ typchecks an application}
+%* *
+%************************************************************************
\begin{code}
-#ifdef DPH
-tcExpr e (ExplicitPodIn exprs)
- = panic "Ignoring explicit PODs for the time being"
-{-
- = tcExprs e exprs `thenTc` (\ (exprs',lie,tys) ->
- newPolyTyVarTy `thenNF_Tc` (\ elt_ty ->
- newDict processorClass elt_ty `thenNF_Tc` (\ procDict ->
- let
- procLie = mkLIEFromDicts procDict
- in
- unifyTauTyList (elt_ty:tys) (PodCtxt exprs) `thenTc_`
-
- returnTc ((App
- (DictApp
- (TyApp (Var toPodId) [elt_ty])
- procDict)
- (ExplicitListOut elt_ty exprs')),
- plusLIE procLie lie,
- mkPodTy elt_ty)
- ))) -}
-#endif {- Data Parallel Haskell -}
+
+tcApp :: LHsExpr Name -> [LHsExpr Name] -- Function and args
+ -> Expected TcRhoType -- Expected result type of application
+ -> TcM (HsExpr TcId) -- Translated fun and args
+
+tcApp (L _ (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
+ tcInferRho fun `thenM` \ (fun', fun_ty) ->
+
+ addErrCtxt (wrongArgsCtxt "too many" fun args) (
+ traceTc (text "tcApp" <+> (ppr fun $$ ppr fun_ty)) `thenM_`
+ split_fun_ty fun_ty (length args)
+ ) `thenM` \ (expected_arg_tys, actual_result_ty) ->
+
+ -- Unify with expected result before (was: after) type-checking the args
+ -- so that the info from res_ty (was: args) percolates to args (was actual_result_ty).
+ -- This is when we might detect a too-few args situation.
+ -- (One can think of cases when the opposite order would give
+ -- a better error message.)
+ -- [March 2003: I'm experimenting with putting this first. Here's an
+ -- example where it actually makes a real difference
+ -- class C t a b | t a -> b
+ -- instance C Char a Bool
+ --
+ -- data P t a = forall b. (C t a b) => MkP b
+ -- data Q t = MkQ (forall a. P t a)
+
+ -- f1, f2 :: Q Char;
+ -- f1 = MkQ (MkP True)
+ -- f2 = MkQ (MkP True :: forall a. P Char a)
+ --
+ -- With the change, f1 will type-check, because the 'Char' info from
+ -- the signature is propagated into MkQ's argument. With the check
+ -- in the other order, the extra signature in f2 is reqd.]
+
+ addErrCtxtM (checkArgsCtxt fun args res_ty actual_result_ty)
+ (tcSubExp res_ty actual_result_ty) `thenM` \ co_fn ->
+
+ -- Now typecheck the args
+ mappM (tcArg fun)
+ (zip3 args expected_arg_tys [1..]) `thenM` \ args' ->
+
+ returnM (co_fn <$> unLoc (foldl mkHsApp fun' args'))
+
+
+-- If an error happens we try to figure out whether the
+-- function has been given too many or too few arguments,
+-- and say so.
+-- The ~(Check...) is because in the Infer case the tcSubExp
+-- definitely won't fail, so we can be certain we're in the Check branch
+checkArgsCtxt fun args ~(Check expected_res_ty) actual_res_ty tidy_env
+ = zonkTcType expected_res_ty `thenM` \ exp_ty' ->
+ zonkTcType actual_res_ty `thenM` \ act_ty' ->
+ let
+ (env1, exp_ty'') = tidyOpenType tidy_env exp_ty'
+ (env2, act_ty'') = tidyOpenType env1 act_ty'
+ (exp_args, _) = tcSplitFunTys exp_ty''
+ (act_args, _) = tcSplitFunTys act_ty''
+
+ len_act_args = length act_args
+ len_exp_args = length exp_args
+
+ message | len_exp_args < len_act_args = wrongArgsCtxt "too few" fun args
+ | len_exp_args > len_act_args = wrongArgsCtxt "too many" fun args
+ | otherwise = appCtxt fun args
+ in
+ returnM (env2, message)
+
+
+split_fun_ty :: TcRhoType -- The type of the function
+ -> Int -- Number of arguments
+ -> TcM ([TcType], -- Function argument types
+ TcType) -- Function result types
+
+split_fun_ty fun_ty 0
+ = returnM ([], fun_ty)
+
+split_fun_ty fun_ty n
+ = -- Expect the function to have type A->B
+ unifyFunTy fun_ty `thenM` \ (arg_ty, res_ty) ->
+ split_fun_ty res_ty (n-1) `thenM` \ (arg_tys, final_res_ty) ->
+ returnM (arg_ty:arg_tys, final_res_ty)
\end{code}
\begin{code}
-#ifdef DPH
-tcExpr e (ExplicitProcessor exprs expr)
- = tcPidExprs e exprs `thenTc` (\ (exprs',lie1,tys) ->
- tcExpr e expr `thenTc` (\ (expr',lie2,ty) ->
- returnTc (ExplicitProcessor exprs' expr',
- plusLIE lie1 lie2,
- mkProcessorTy tys ty)
- ))
-#endif {- Data Parallel Haskell -}
+tcArg :: LHsExpr Name -- The function (for error messages)
+ -> (LHsExpr Name, TcSigmaType, Int) -- Actual argument and expected arg type
+ -> TcM (LHsExpr TcId) -- Resulting argument
+
+tcArg the_fun (arg, expected_arg_ty, arg_no)
+ = addErrCtxt (funAppCtxt the_fun arg arg_no) $
+ tcCheckSigma arg expected_arg_ty
\end{code}
+
%************************************************************************
%* *
-\subsection{@tcExprs@ typechecks a {\em list} of expressions}
+\subsection{@tcId@ typchecks an identifier occurrence}
%* *
%************************************************************************
-ToDo: Possibly find a version of a listTc TcM which would pass the
-appropriate functions for the LIE.
+tcId instantiates an occurrence of an Id.
+The instantiate_it loop runs round instantiating the Id.
+It has to be a loop because we are now prepared to entertain
+types like
+ f:: forall a. Eq a => forall b. Baz b => tau
+We want to instantiate this to
+ f2::tau {f2 = f1 b (Baz b), f1 = f a (Eq a)}
+
+The -fno-method-sharing flag controls what happens so far as the LIE
+is concerned. The default case is that for an overloaded function we
+generate a "method" Id, and add the Method Inst to the LIE. So you get
+something like
+ f :: Num a => a -> a
+ f = /\a (d:Num a) -> let m = (+) a d in \ (x:a) -> m x x
+If you specify -fno-method-sharing, the dictionary application
+isn't shared, so we get
+ f :: Num a => a -> a
+ f = /\a (d:Num a) (x:a) -> (+) a d x x
+This gets a bit less sharing, but
+ a) it's better for RULEs involving overloaded functions
+ b) perhaps fewer separated lambdas
\begin{code}
-tcExprs :: E -> [RenamedExpr] -> TcM ([TypecheckedExpr],LIE,[TauType])
+tcId :: Name -> TcM (HsExpr TcId, TcRhoType)
+tcId name -- Look up the Id and instantiate its type
+ = -- First check whether it's a DataCon
+ -- Reason: we must not forget to chuck in the
+ -- constraints from their "silly context"
+ tcLookup name `thenM` \ thing ->
+ case thing of {
+ AGlobal (ADataCon data_con) -> inst_data_con data_con
+ ; AGlobal (AnId id) -> loop (HsVar id) (idType id)
+ -- A global cannot possibly be ill-staged
+ -- nor does it need the 'lifting' treatment
+
+ ; ATcId id th_level proc_level -> tc_local_id id th_level proc_level
+ ; other -> pprPanic "tcId" (ppr name $$ ppr thing)
+ }
+ where
-tcExprs e [] = returnTc ([], nullLIE, [])
-tcExprs e (expr:exprs)
- = tcExpr e expr `thenTc` \ (expr', lie1, ty) ->
- tcExprs e exprs `thenTc` \ (exprs', lie2, tys) ->
- returnTc (expr':exprs', plusLIE lie1 lie2, ty:tys)
+#ifndef GHCI
+ tc_local_id id th_bind_lvl proc_lvl -- Non-TH case
+ = checkProcLevel id proc_lvl `thenM_`
+ loop (HsVar id) (idType id)
+
+#else /* GHCI and TH is on */
+ tc_local_id id th_bind_lvl proc_lvl -- TH case
+ = checkProcLevel id proc_lvl `thenM_`
+
+ -- Check for cross-stage lifting
+ getStage `thenM` \ use_stage ->
+ case use_stage of
+ Brack use_lvl ps_var lie_var
+ | use_lvl > th_bind_lvl
+ -> -- E.g. \x -> [| h x |]
+ -- We must behave as if the reference to x was
+
+ -- h $(lift x)
+ -- We use 'x' itself as the splice proxy, used by
+ -- the desugarer to stitch it all back together.
+ -- If 'x' occurs many times we may get many identical
+ -- bindings of the same splice proxy, but that doesn't
+ -- matter, although it's a mite untidy.
+ let
+ id_ty = idType id
+ in
+ checkTc (isTauTy id_ty) (polySpliceErr id) `thenM_`
+ -- If x is polymorphic, its occurrence sites might
+ -- have different instantiations, so we can't use plain
+ -- 'x' as the splice proxy name. I don't know how to
+ -- solve this, and it's probably unimportant, so I'm
+ -- just going to flag an error for now
+
+ setLIEVar lie_var (
+ newMethodFromName orig id_ty DsMeta.liftName `thenM` \ lift ->
+ -- Put the 'lift' constraint into the right LIE
+
+ -- Update the pending splices
+ readMutVar ps_var `thenM` \ ps ->
+ writeMutVar ps_var ((name, nlHsApp (nlHsVar lift) (nlHsVar id)) : ps) `thenM_`
+
+ returnM (HsVar id, id_ty))
+
+ other ->
+ checkWellStaged (quotes (ppr id)) th_bind_lvl use_stage `thenM_`
+ loop (HsVar id) (idType id)
+#endif /* GHCI */
+
+ loop (HsVar fun_id) fun_ty
+ | want_method_inst fun_ty
+ = tcInstType VanillaTv fun_ty `thenM` \ (tyvars, theta, tau) ->
+ newMethodWithGivenTy orig fun_id
+ (mkTyVarTys tyvars) theta tau `thenM` \ meth_id ->
+ loop (HsVar meth_id) tau
+
+ loop fun fun_ty
+ | isSigmaTy fun_ty
+ = tcInstCall orig fun_ty `thenM` \ (inst_fn, tau) ->
+ loop (inst_fn <$> fun) tau
+
+ | otherwise
+ = returnM (fun, fun_ty)
+
+ -- Hack Alert (want_method_inst)!
+ -- If f :: (%x :: T) => Int -> Int
+ -- Then if we have two separate calls, (f 3, f 4), we cannot
+ -- make a method constraint that then gets shared, thus:
+ -- let m = f %x in (m 3, m 4)
+ -- because that loses the linearity of the constraint.
+ -- The simplest thing to do is never to construct a method constraint
+ -- in the first place that has a linear implicit parameter in it.
+ want_method_inst fun_ty
+ | opt_NoMethodSharing = False
+ | otherwise = case tcSplitSigmaTy fun_ty of
+ (_,[],_) -> False -- Not overloaded
+ (_,theta,_) -> not (any isLinearPred theta)
+
+
+ -- We treat data constructors differently, because we have to generate
+ -- constraints for their silly theta, which no longer appears in
+ -- the type of dataConWrapId (see note on "stupid context" in DataCon.lhs
+ -- It's dual to TcPat.tcConstructor
+ inst_data_con data_con
+ = tcInstDataCon orig data_con `thenM` \ (ty_args, ex_dicts, arg_tys, result_ty, _) ->
+ extendLIEs ex_dicts `thenM_`
+ getSrcSpanM `thenM` \ loc ->
+ returnM (unLoc (mkHsDictApp (mkHsTyApp (L loc (HsVar (dataConWrapId data_con))) ty_args)
+ (map instToId ex_dicts)),
+ mkFunTys arg_tys result_ty)
+ -- ToDo: nasty loc/unloc stuff here
+
+ orig = OccurrenceOf name
\end{code}
-
%************************************************************************
%* *
-\subsection{@tcApp@ typchecks an application}
+\subsection{Record bindings}
%* *
%************************************************************************
-\begin{code}
-tcApp :: (TypecheckedExpr -> [TypecheckedExpr] -> TypecheckedExpr) -- Result builder
- -> E
- -> RenamedExpr
- -> [RenamedExpr]
- -> TcM (TypecheckedExpr, LIE, UniType)
-
-tcApp build_result_expression e orig_fun arg_exprs
- = tcExpr' e orig_fun (length arg_exprs)
- `thenTc` \ (fun', lie_fun, fun_ty) ->
- unify_fun 1 fun' lie_fun arg_exprs fun_ty
- where
- -- Used only in the error message
- maybe_fun_id = case orig_fun of
- Var name -> Just (lookupE_Value e name)
- other -> Nothing
-
- unify_args :: Int -- Current argument number
- -> TypecheckedExpr -- Current rebuilt expression
- -> LIE -- Corresponding LIE
- -> [RenamedExpr] -- Remaining args
- -> [TauType] -- Remaining arg types
- -> TauType -- result type
- -> TcM (TypecheckedExpr, LIE, UniType)
-
- unify_args arg_no fun lie (arg:args) (arg_ty:arg_tys) fun_res_ty
- = tcExpr e arg `thenTc` \ (arg', lie_arg, actual_arg_ty) ->
-
- -- These applyTcSubstToTy's are just to improve the error message...
- applyTcSubstToTy actual_arg_ty `thenNF_Tc` \ actual_arg_ty' ->
- applyTcSubstToTy arg_ty `thenNF_Tc` \ arg_ty' ->
- let
- err_ctxt = FunAppCtxt orig_fun maybe_fun_id arg arg_ty' actual_arg_ty' arg_no
- in
- matchArgTy e arg_ty' arg' lie_arg actual_arg_ty' err_ctxt
- `thenTc` \ (arg'', lie_arg') ->
+Game plan for record bindings
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+1. Find the TyCon for the bindings, from the first field label.
+
+2. Instantiate its tyvars and unify (T a1 .. an) with expected_ty.
- unify_args (arg_no+1) (App fun arg'') (lie `plusLIE` lie_arg') args arg_tys fun_res_ty
+For each binding field = value
- unify_args arg_no fun lie [] arg_tys fun_res_ty
- = -- We've run out of actual arguments Check that none of
- -- arg_tys has a for-all at the top For example, "build" on
- -- its own is no good; it must be applied to something.
+3. Instantiate the field type (from the field label) using the type
+ envt from step 2.
+
+4 Type check the value using tcArg, passing the field type as
+ the expected argument type.
+
+This extends OK when the field types are universally quantified.
+
+
+\begin{code}
+tcRecordBinds
+ :: TyCon -- Type constructor for the record
+ -> [TcType] -- Args of this type constructor
+ -> HsRecordBinds Name
+ -> TcM (HsRecordBinds TcId)
+
+tcRecordBinds tycon ty_args rbinds
+ = mappM do_bind rbinds
+ where
+ tenv = mkTopTyVarSubst (tyConTyVars tycon) ty_args
+
+ do_bind (L loc field_lbl_name, rhs)
+ = addErrCtxt (fieldCtxt field_lbl_name) $
+ tcLookupId field_lbl_name `thenM` \ sel_id ->
let
- result_ty = glueTyArgs arg_tys fun_res_ty
+ field_lbl = recordSelectorFieldLabel sel_id
+ field_ty = substTy tenv (fieldLabelType field_lbl)
in
- checkTc (not (isTauTy result_ty))
- (error "ERROR: 2 rank failure (NEED ERROR MSG [ToDo])") `thenTc_`
- returnTc (fun, lie, result_ty)
+ ASSERT( isRecordSelector sel_id )
+ -- This lookup and assertion will surely succeed, because
+ -- we check that the fields are indeed record selectors
+ -- before calling tcRecordBinds
+ ASSERT2( fieldLabelTyCon field_lbl == tycon, ppr field_lbl )
+ -- The caller of tcRecordBinds has already checked
+ -- that all the fields come from the same type
+
+ tcCheckSigma rhs field_ty `thenM` \ rhs' ->
- -- When we run out of arg_tys we go back to unify_fun in the hope
- -- that our unification work may have shown up some more arguments
- unify_args arg_no fun lie args [] fun_res_ty
- = unify_fun arg_no fun lie args fun_res_ty
+ returnM (L loc sel_id, rhs')
+badFields rbinds data_con
+ = filter (not . (`elem` field_names)) (recBindFields rbinds)
+ where
+ field_names = map fieldLabelName (dataConFieldLabels data_con)
+
+checkMissingFields :: DataCon -> HsRecordBinds Name -> TcM ()
+checkMissingFields data_con rbinds
+ | null field_labels -- Not declared as a record;
+ -- But C{} is still valid if no strict fields
+ = if any isMarkedStrict field_strs then
+ -- Illegal if any arg is strict
+ addErrTc (missingStrictFields data_con [])
+ else
+ returnM ()
+
+ | otherwise -- A record
+ = checkM (null missing_s_fields)
+ (addErrTc (missingStrictFields data_con missing_s_fields)) `thenM_`
- unify_fun :: Int -- Current argument number
- -> TypecheckedExpr -- Current rebuilt expression
- -> LIE -- Corresponding LIE
- -> [RenamedExpr] -- Remaining args
- -> TauType -- Remaining function type
- -> TcM (TypecheckedExpr, LIE, UniType)
+ doptM Opt_WarnMissingFields `thenM` \ warn ->
+ checkM (not (warn && notNull missing_ns_fields))
+ (warnTc True (missingFields data_con missing_ns_fields))
- unify_fun arg_no fun lie args fun_ty
- = -- Find out as much as possible about the function
- applyTcSubstToTy fun_ty `thenNF_Tc` \ fun_ty' ->
+ where
+ missing_s_fields
+ = [ fl | (fl, str) <- field_info,
+ isMarkedStrict str,
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+ missing_ns_fields
+ = [ fl | (fl, str) <- field_info,
+ not (isMarkedStrict str),
+ not (fieldLabelName fl `elem` field_names_used)
+ ]
+
+ field_names_used = recBindFields rbinds
+ field_labels = dataConFieldLabels data_con
+
+ field_info = zipEqual "missingFields"
+ field_labels
+ field_strs
+
+ field_strs = dataConStrictMarks data_con
+\end{code}
- -- Now see whether it has any arguments
- case (splitTyArgs fun_ty') of
+%************************************************************************
+%* *
+\subsection{@tcCheckRhos@ typechecks a {\em list} of expressions}
+%* *
+%************************************************************************
- ([], _) -> -- Function has no arguments left
+\begin{code}
+tcCheckRhos :: [LHsExpr Name] -> [TcType] -> TcM [LHsExpr TcId]
- newOpenTyVarTy `thenNF_Tc` \ result_ty ->
- tcExprs e args `thenTc` \ (args', lie_args, arg_tys) ->
+tcCheckRhos [] [] = returnM []
+tcCheckRhos (expr:exprs) (ty:tys)
+ = tcCheckRho expr ty `thenM` \ expr' ->
+ tcCheckRhos exprs tys `thenM` \ exprs' ->
+ returnM (expr':exprs')
+\end{code}
- -- At this point, a unification error must mean the function is
- -- being applied to too many arguments.
- unifyTauTy fun_ty' (glueTyArgs arg_tys result_ty)
- (TooManyArgsCtxt orig_fun) `thenTc_`
- returnTc (build_result_expression fun args',
- lie `plusLIE` lie_args,
- result_ty)
+%************************************************************************
+%* *
+\subsection{Literals}
+%* *
+%************************************************************************
- (fun_arg_tys, fun_res_ty) -> -- Function has non-empty list of argument types
+Overloaded literals.
- unify_args arg_no fun lie args fun_arg_tys fun_res_ty
+\begin{code}
+tcLit :: HsLit -> Expected TcRhoType -> TcM (HsExpr TcId)
+tcLit lit res_ty
+ = zapExpectedTo res_ty (hsLitType lit) `thenM_`
+ returnM (HsLit lit)
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
+Boring and alphabetical:
\begin{code}
-matchArgTy :: E
- -> UniType -- Expected argument type
- -> TypecheckedExpr -- Type checked argument
- -> LIE -- Actual argument LIE
- -> UniType -- Actual argument type
- -> UnifyErrContext
- -> TcM (TypecheckedExpr, -- The incoming type checked arg,
- -- possibly wrapped in a big lambda
- LIE) -- Possibly reduced somewhat
-
-matchArgTy e expected_arg_ty arg_expr actual_arg_lie actual_arg_ty err_ctxt
- | isForAllTy expected_arg_ty
- = -- Ha! The argument type of the function is a for-all type,
- -- An example of rank-2 polymorphism.
-
- -- This applyTcSubstToTy is just to improve the error message..
-
- applyTcSubstToTy actual_arg_ty `thenNF_Tc` \ actual_arg_ty' ->
-
- -- Instantiate the argument type
- -- ToDo: give this a real origin
- specTy UnknownOrigin expected_arg_ty `thenNF_Tc` \ (arg_tyvars, arg_lie, arg_tau) ->
-
- if not (null arg_lie) then
- -- Paranoia check
- panic "Non-null overloading in tcApp"
- else
- -- Assert: arg_lie = []
-
- unifyTauTy arg_tau actual_arg_ty' err_ctxt `thenTc_`
-
- -- Check that the arg_tyvars havn't been constrained
- -- The interesting bit here is that we must include the free variables
- -- of the expected arg ty. Here's an example:
- -- runST (newVar True)
- -- Here, if we don't make a check, we'll get a type (ST s (MutVar s Bool))
- -- for (newVar True), with s fresh. Then we unify with the runST's arg type
- -- forall s'. ST s' a. That unifies s' with s, and a with MutVar s Bool.
- -- So now s' isn't unconstrained because it's linked to a.
- -- Conclusion: include the free vars of the expected arg type in the
- -- list of "free vars" for the signature check.
- applyTcSubstAndCollectTyVars
- (tvOfE e `unionLists`
- extractTyVarsFromTy expected_arg_ty) `thenNF_Tc` \ free_tyvars ->
- checkSigTyVars free_tyvars arg_tyvars arg_tau actual_arg_ty rank2_err_ctxt
- `thenTc` \ arg_tyvars' ->
-
- -- Check that there's no overloading involved
- -- Even if there isn't, there may be some Insts which mention the arg_tyvars,
- -- but which, on simplification, don't actually need a dictionary involving
- -- the tyvar. So we have to do a proper simplification right here.
- let insts = unMkLIE actual_arg_lie
- in
- applyTcSubstToInsts insts `thenNF_Tc` \ insts' ->
+arithSeqCtxt expr
+ = hang (ptext SLIT("In an arithmetic sequence:")) 4 (ppr expr)
+
+parrSeqCtxt expr
+ = hang (ptext SLIT("In a parallel array sequence:")) 4 (ppr expr)
+
+caseCtxt expr
+ = hang (ptext SLIT("In the case expression:")) 4 (ppr expr)
- tcSimplifyRank2 arg_tyvars' insts' rank2_err_ctxt `thenTc` \ (free_insts, inst_binds) ->
+caseScrutCtxt expr
+ = hang (ptext SLIT("In the scrutinee of a case expression:")) 4 (ppr expr)
- -- This Let 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 arg_tyvars' (Let (mk_binds inst_binds) arg_expr), mkLIE free_insts)
+exprCtxt expr
+ = hang (ptext SLIT("In the expression:")) 4 (ppr expr)
- | otherwise
- = -- The ordinary, non-rank-2 polymorphic case
- unifyTauTy expected_arg_ty actual_arg_ty err_ctxt `thenTc_`
- returnTc (arg_expr, actual_arg_lie)
+fieldCtxt field_name
+ = ptext SLIT("In the") <+> quotes (ppr field_name) <+> ptext SLIT("field of a record")
+funAppCtxt fun arg arg_no
+ = hang (hsep [ ptext SLIT("In the"), speakNth arg_no, ptext SLIT("argument of"),
+ quotes (ppr fun) <> text ", namely"])
+ 4 (quotes (ppr arg))
+
+listCtxt expr
+ = hang (ptext SLIT("In the list element:")) 4 (ppr expr)
+
+parrCtxt expr
+ = hang (ptext SLIT("In the parallel array element:")) 4 (ppr expr)
+
+predCtxt expr
+ = hang (ptext SLIT("In the predicate expression:")) 4 (ppr expr)
+
+appCtxt fun args
+ = ptext SLIT("In the application") <+> quotes (ppr the_app)
where
- rank2_err_ctxt = Rank2ArgCtxt arg_expr expected_arg_ty
+ the_app = foldl mkHsApp fun args -- Used in error messages
- mk_binds [] = EmptyBinds
- mk_binds ((inst,rhs):inst_binds) = (SingleBind (NonRecBind (VarMonoBind (mkInstId inst) rhs)))
- `ThenBinds`
- mk_binds inst_binds
-\end{code}
+badFieldsUpd rbinds
+ = hang (ptext SLIT("No constructor has all these fields:"))
+ 4 (pprQuotedList (recBindFields rbinds))
-This version only does not check for 2nd order if it is applied.
+recordUpdCtxt expr = ptext SLIT("In the record update:") <+> ppr expr
+recordConCtxt expr = ptext SLIT("In the record construction:") <+> ppr expr
-\begin{code}
-tcExpr' :: E -> RenamedExpr -> Int -> TcM (TypecheckedExpr,LIE,UniType)
+notSelector field
+ = hsep [quotes (ppr field), ptext SLIT("is not a record selector")]
-tcExpr' e v@(Var name) n
- | n > 0 = specId (lookupE_Value e name) `thenNF_Tc` \ (expr, lie, ty) ->
- returnTc (expr, lie, ty)
-tcExpr' e exp n = tcExpr e exp
+missingStrictFields :: DataCon -> [FieldLabel] -> SDoc
+missingStrictFields con fields
+ = header <> rest
+ where
+ rest | null fields = empty -- Happens for non-record constructors
+ -- with strict fields
+ | otherwise = colon <+> pprWithCommas ppr fields
+
+ header = ptext SLIT("Constructor") <+> quotes (ppr con) <+>
+ ptext SLIT("does not have the required strict field(s)")
+
+missingFields :: DataCon -> [FieldLabel] -> SDoc
+missingFields con fields
+ = ptext SLIT("Fields of") <+> quotes (ppr con) <+> ptext SLIT("not initialised:")
+ <+> pprWithCommas ppr fields
+
+wrongArgsCtxt too_many_or_few fun args
+ = hang (ptext SLIT("Probable cause:") <+> quotes (ppr fun)
+ <+> ptext SLIT("is applied to") <+> text too_many_or_few
+ <+> ptext SLIT("arguments in the call"))
+ 4 (parens (ppr the_app))
+ where
+ the_app = foldl mkHsApp fun args -- Used in error messages
+
+#ifdef GHCI
+polySpliceErr :: Id -> SDoc
+polySpliceErr id
+ = ptext SLIT("Can't splice the polymorphic local variable") <+> quotes (ppr id)
+#endif
\end{code}
projects / ghc-hetmet.git / blobdiff