%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1995
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcPat]{Typechecking patterns}
\begin{code}
+module TcPat ( tcPat, tcMonoPatBndr, tcSubPat,
+ badFieldCon, polyPatSig
+ ) where
+
#include "HsVersions.h"
-module TcPat (
- tcPat
-#ifdef DPH
- , tcPats
-#endif
- ) where
-
-import TcMonad -- typechecking monad machinery
-import TcMonadFns ( newOpenTyVarTy, newPolyTyVarTy,
- newPolyTyVarTys, copyTyVars, newMethod,
- newOverloadedLit
- )
-import AbsSyn -- the stuff being typechecked
-
-import AbsPrel ( charPrimTy, intPrimTy, floatPrimTy,
- doublePrimTy, charTy, stringTy, mkListTy,
- mkTupleTy, addrTy, addrPrimTy, --OLD: eqStringId
- PrimOp
- IF_ATTACK_PRAGMAS(COMMA tagOf_PrimOp)
- IF_ATTACK_PRAGMAS(COMMA pprPrimOp)
-#ifdef DPH
- ,mkProcessorTy, toDomainId
-#endif {- Data Parallel Haskell -}
- )
-import AbsUniType ( instantiateTauTy, applyTyCon, InstTyEnv(..)
- IF_ATTACK_PRAGMAS(COMMA instantiateTy)
- )
-import CmdLineOpts ( GlobalSwitch(..) )
-import Id ( mkInstId, getIdUniType, getDataConSig,
- getInstantiatedDataConSig, Id, DataCon(..)
- )
-import Inst
-import E ( lookupE_Binder, lookupE_Value,
- lookupE_ClassOpByKey, E,
- LVE(..), TCE(..), UniqFM, CE(..)
- -- TCE and CE for pragmas only
- )
-import Errors ( dataConArityErr, Error(..), UnifyErrContext(..)
+import HsSyn ( Pat(..), LPat, HsConDetails(..), HsLit(..), HsOverLit(..), HsExpr(..) )
+import HsUtils
+import TcHsSyn ( TcId, hsLitType,
+ mkCoercion, idCoercion, isIdCoercion,
+ (<$>), PatCoFn )
+
+import TcRnMonad
+import Inst ( InstOrigin(..),
+ newMethodFromName, newOverloadedLit, newDicts,
+ instToId, tcInstDataCon, tcSyntaxName
)
-import LIE ( nullLIE, plusLIE, mkLIE, LIE )
-import Unify
-import Unique -- some ClassKey stuff
-import Util
-
-#ifdef DPH
-import TcParQuals
-#endif {- Data Parallel Haskell -}
+import Id ( idType, mkLocalId, mkSysLocal )
+import Name ( Name )
+import FieldLabel ( fieldLabelName )
+import TcEnv ( tcLookupClass, tcLookupLocatedDataCon, tcLookupId )
+import TcMType ( newTyVarTy, arityErr )
+import TcType ( TcType, TcTyVar, TcSigmaType,
+ mkClassPred, liftedTypeKind )
+import TcUnify ( tcSubOff, Expected(..), readExpectedType, zapExpectedType,
+ unifyTauTy, zapToListTy, zapToPArrTy, zapToTupleTy )
+import TcHsType ( tcHsSigType, UserTypeCtxt(..) )
+
+import TysWiredIn ( stringTy )
+import CmdLineOpts ( opt_IrrefutableTuples )
+import DataCon ( DataCon, dataConFieldLabels, dataConSourceArity )
+import PrelNames ( eqStringName, eqName, geName, negateName, minusName,
+ integralClassName )
+import BasicTypes ( isBoxed )
+import SrcLoc ( Located(..), noLoc, unLoc )
+import Bag
+import Outputable
+import FastString
\end{code}
-The E passed in already contains bindings for all the variables in
-the pattern, usually to fresh type variables (but maybe not, if there
-were type signatures present).
+
+%************************************************************************
+%* *
+\subsection{Variable patterns}
+%* *
+%************************************************************************
\begin{code}
-tcPat :: E -> RenamedPat -> TcM (TypecheckedPat, LIE, UniType)
+type BinderChecker = Name -> Expected TcSigmaType -> TcM (PatCoFn, TcId)
+ -- How to construct a suitable (monomorphic)
+ -- Id for variables found in the pattern
+ -- The TcSigmaType is the expected type
+ -- from the pattern context
+
+-- The Id may have a sigma type (e.g. f (x::forall a. a->a))
+-- so we want to *create* it during pattern type checking.
+-- We don't want to make Ids first with a type-variable type
+-- and then unify... becuase we can't unify a sigma type with a type variable.
+
+tcMonoPatBndr :: BinderChecker
+ -- This is the right function to pass to tcPat when
+ -- we're looking at a lambda-bound pattern,
+ -- so there's no polymorphic guy to worry about
+
+tcMonoPatBndr binder_name pat_ty
+ = zapExpectedType pat_ty `thenM` \ pat_ty' ->
+ -- If there are *no constraints* on the pattern type, we
+ -- revert to good old H-M typechecking, making
+ -- the type of the binder into an *ordinary*
+ -- type variable. We find out if there are no constraints
+ -- by seeing if we are given an "open hole" as our info.
+ -- What we are trying to avoid here is giving a binder
+ -- a type that is a 'hole'. The only place holes should
+ -- appear is as an argument to tcPat and tcExpr/tcMonoExpr.
+
+ returnM (idCoercion, mkLocalId binder_name pat_ty')
\end{code}
+
%************************************************************************
%* *
-\subsection{Variables, wildcards, lazy pats, as-pats}
+\subsection{Typechecking patterns}
%* *
%************************************************************************
\begin{code}
-tcPat e (VarPatIn name)
- = let
- id = lookupE_Binder e name
- in
- returnTc (VarPat id, nullLIE, getIdUniType id)
+tcPat :: BinderChecker
+ -> LPat Name
+
+ -> Expected TcSigmaType -- Expected type derived from the context
+ -- In the case of a function with a rank-2 signature,
+ -- this type might be a forall type.
+
+ -> TcM (LPat TcId,
+ Bag TcTyVar, -- TyVars bound by the pattern
+ -- These are just the existentially-bound ones.
+ -- Any tyvars bound by *type signatures* in the
+ -- patterns are brought into scope before we begin.
+ Bag (Name, TcId), -- Ids bound by the pattern, along with the Name under
+ -- which it occurs in the pattern
+ -- The two aren't the same because we conjure up a new
+ -- local name for each variable.
+ [Inst]) -- Dicts or methods [see below] bound by the pattern
+ -- from existential constructor patterns
+tcPat tc_bndr (L span pat) exp_ty
+ = addSrcSpan span $
+ do { (pat', tvs, ids, lie) <- tc_pat tc_bndr pat exp_ty
+ ; return (L span pat', tvs, ids, lie) }
+\end{code}
-tcPat e (LazyPatIn pat)
- = tcPat e pat `thenTc` \ (pat', lie, ty) ->
- returnTc (LazyPat pat', lie, ty)
-tcPat e pat_in@(AsPatIn name pat)
- = let
- id = lookupE_Binder e name
- in
- tcPat e pat `thenTc` \ (pat', lie, ty) ->
- unifyTauTy (getIdUniType id) ty (PatCtxt pat_in) `thenTc_`
- returnTc (AsPat id pat', lie, ty)
+%************************************************************************
+%* *
+\subsection{Variables, wildcards, lazy pats, as-pats}
+%* *
+%************************************************************************
-tcPat e (WildPatIn)
- = newOpenTyVarTy `thenNF_Tc` \ tyvar_ty ->
- returnTc (WildPat tyvar_ty, nullLIE, tyvar_ty)
+\begin{code}
+tc_pat tc_bndr pat@(TypePat ty) pat_ty
+ = failWithTc (badTypePat pat)
+
+tc_pat tc_bndr (VarPat name) pat_ty
+ = tc_bndr name pat_ty `thenM` \ (co_fn, bndr_id) ->
+ returnM (co_fn <$> VarPat bndr_id,
+ emptyBag, unitBag (name, bndr_id), [])
+
+tc_pat tc_bndr (LazyPat pat) pat_ty
+ = tcPat tc_bndr pat pat_ty `thenM` \ (pat', tvs, ids, lie_avail) ->
+ returnM (LazyPat pat', tvs, ids, lie_avail)
+
+tc_pat tc_bndr pat_in@(AsPat (L nm_loc name) pat) pat_ty
+ = addSrcSpan nm_loc (tc_bndr name pat_ty) `thenM` \ (co_fn, bndr_id) ->
+ tcPat tc_bndr pat (Check (idType bndr_id)) `thenM` \ (pat', tvs, ids, lie_avail) ->
+ -- NB: if we have:
+ -- \ (y@(x::forall a. a->a)) = e
+ -- we'll fail. The as-pattern infers a monotype for 'y', which then
+ -- fails to unify with the polymorphic type for 'x'. This could be
+ -- fixed, but only with a bit more work.
+ returnM (co_fn <$> (AsPat (L nm_loc bndr_id) pat'),
+ tvs, (name, bndr_id) `consBag` ids, lie_avail)
+
+tc_pat tc_bndr (WildPat _) pat_ty
+ = zapExpectedType pat_ty `thenM` \ pat_ty' ->
+ -- We might have an incoming 'hole' type variable; no annotation
+ -- so zap it to a type. Rather like tcMonoPatBndr.
+ returnM (WildPat pat_ty', emptyBag, emptyBag, [])
+
+tc_pat tc_bndr (ParPat parend_pat) pat_ty
+-- Leave the parens in, so that warnings from the
+-- desugarer have parens in them
+ = tcPat tc_bndr parend_pat pat_ty `thenM` \ (pat', tvs, ids, lie_avail) ->
+ returnM (ParPat pat', tvs, ids, lie_avail)
+
+tc_pat tc_bndr pat_in@(SigPatIn pat sig) pat_ty
+ = addErrCtxt (patCtxt pat_in) $
+ tcHsSigType PatSigCtxt sig `thenM` \ sig_ty ->
+ tcSubPat sig_ty pat_ty `thenM` \ co_fn ->
+ tcPat tc_bndr pat (Check sig_ty) `thenM` \ (pat', tvs, ids, lie_avail) ->
+ returnM (co_fn <$> unLoc pat', tvs, ids, lie_avail)
\end{code}
+
%************************************************************************
%* *
-\subsection{Explicit lists and tuples}
+\subsection{Explicit lists, parallel arrays, and tuples}
%* *
%************************************************************************
\begin{code}
-tcPat e pat_in@(ListPatIn pats)
- = tcPats e pats `thenTc` \ (pats', lie, tys) ->
- newPolyTyVarTy `thenNF_Tc` \ tyvar_ty ->
-
- unifyTauTyList (tyvar_ty:tys) (PatCtxt pat_in) `thenTc_`
-
- returnTc (ListPat tyvar_ty pats', lie, mkListTy tyvar_ty)
+tc_pat tc_bndr pat_in@(ListPat pats _) pat_ty
+ = addErrCtxt (patCtxt pat_in) $
+ zapToListTy pat_ty `thenM` \ elem_ty ->
+ tcPats tc_bndr pats (repeat elem_ty) `thenM` \ (pats', tvs, ids, lie_avail) ->
+ returnM (ListPat pats' elem_ty, tvs, ids, lie_avail)
-tcPat e pat_in@(TuplePatIn pats)
- = let
- arity = length pats
- in
- tcPats e pats `thenTc` \ (pats', lie, tys) ->
+tc_pat tc_bndr pat_in@(PArrPat pats _) pat_ty
+ = addErrCtxt (patCtxt pat_in) $
+ zapToPArrTy pat_ty `thenM` \ elem_ty ->
+ tcPats tc_bndr pats (repeat elem_ty) `thenM` \ (pats', tvs, ids, lie_avail) ->
+ returnM (PArrPat pats' elem_ty, tvs, ids, lie_avail)
- -- We have to unify with fresh polymorphic type variables, to
- -- make sure we record that the tuples can only contain boxed
- -- types.
- newPolyTyVarTys arity `thenNF_Tc` \ tyvar_tys ->
+tc_pat tc_bndr pat_in@(TuplePat pats boxity) pat_ty
+ = addErrCtxt (patCtxt pat_in) $
- unifyTauTyLists tyvar_tys tys (PatCtxt pat_in) `thenTc_`
+ zapToTupleTy boxity arity pat_ty `thenM` \ arg_tys ->
+ tcPats tc_bndr pats arg_tys `thenM` \ (pats', tvs, ids, lie_avail) ->
-- possibly do the "make all tuple-pats irrefutable" test:
- getSwitchCheckerTc `thenNF_Tc` \ sw_chkr ->
let
- unmangled_result = TuplePat pats'
+ unmangled_result = TuplePat pats' boxity
-- Under flag control turn a pattern (x,y,z) into ~(x,y,z)
-- so that we can experiment with lazy tuple-matching.
-- This is a pretty odd place to make the switch, but
-- it was easy to do.
- possibly_mangled_result
- = if sw_chkr IrrefutableTuples
- then LazyPat unmangled_result
- else unmangled_result
- -- ToDo: IrrefutableEverything
+ possibly_mangled_result
+ | opt_IrrefutableTuples && isBoxed boxity = LazyPat (noLoc unmangled_result)
+ | otherwise = unmangled_result
in
- returnTc (possibly_mangled_result, lie, mkTupleTy arity tys)
+ returnM (possibly_mangled_result, tvs, ids, lie_avail)
+ where
+ arity = length pats
\end{code}
+
%************************************************************************
%* *
\subsection{Other constructors}
%* *
-%************************************************************************
-Constructor patterns are a little fun:
-\begin{itemize}
-\item
-typecheck the arguments
-\item
-look up the constructor
-\item
-specialise its type (ignore the translation this produces)
-\item
-check that the context produced by this specialisation is empty
-\item
-get the arguments out of the function type produced from specialising
-\item
-unify them with the types of the patterns
-\item
-back substitute with the type of the result of the constructor
-\end{itemize}
-
-ToDo: exploit new representation of constructors to make this more
-efficient?
+%************************************************************************
\begin{code}
-tcPat e pat_in@(ConPatIn name pats)
- = let
- con_id = lookupE_Value e name
- in
- tcPats e pats `thenTc` \ (pats', lie, tys) ->
+tc_pat tc_bndr pat_in@(ConPatIn con_name arg_pats) pat_ty
+ = addErrCtxt (patCtxt pat_in) $
- matchConArgTys con_id tys (\ ty -> PatCtxt pat_in) `thenTc` \ data_ty ->
+ -- Check that it's a constructor, and instantiate it
+ tcLookupLocatedDataCon con_name `thenM` \ data_con ->
+ tcInstDataCon (PatOrigin pat_in) data_con `thenM` \ (_, ex_dicts1, arg_tys, con_res_ty, ex_tvs) ->
- returnTc (ConPat con_id data_ty pats', lie, data_ty)
+ -- Check overall type matches.
+ -- The pat_ty might be a for-all type, in which
+ -- case we must instantiate to match
+ tcSubPat con_res_ty pat_ty `thenM` \ co_fn ->
-tcPat e pat_in@(ConOpPatIn pat1 op pat2) -- & in binary-op form...
- = let
- con_id = lookupE_Value e op
- in
- tcPats e [pat1, pat2] `thenTc` \ ([pat1',pat2'], lie, tys) ->
- -- ToDo: there exists a less ugly way, no doubt...
-
- matchConArgTys con_id tys (\ ty -> PatCtxt pat_in) `thenTc` \ data_ty ->
+ -- Check the argument patterns
+ tcConStuff tc_bndr data_con arg_pats arg_tys `thenM` \ (arg_pats', arg_tvs, arg_ids, ex_dicts2) ->
- returnTc (ConOpPat pat1' con_id pat2' data_ty, lie, data_ty)
+ returnM (co_fn <$> ConPatOut data_con arg_pats' con_res_ty ex_tvs (map instToId ex_dicts1),
+ listToBag ex_tvs `unionBags` arg_tvs,
+ arg_ids,
+ ex_dicts1 ++ ex_dicts2)
\end{code}
+
%************************************************************************
%* *
-\subsection{Non-overloaded literals}
+\subsection{Literals}
%* *
%************************************************************************
\begin{code}
-tcPat e (LitPatIn lit@(CharLit str))
- = returnTc (LitPat lit charTy, nullLIE, charTy)
+tc_pat tc_bndr pat@(LitPat lit@(HsString _)) pat_ty
+ = zapExpectedType pat_ty `thenM` \ pat_ty' ->
+ unifyTauTy pat_ty' stringTy `thenM_`
+ tcLookupId eqStringName `thenM` \ eq_id ->
+ returnM (NPatOut lit stringTy (nlHsVar eq_id `HsApp` nlHsLit lit),
+ emptyBag, emptyBag, [])
+
+tc_pat tc_bndr (LitPat simple_lit) pat_ty
+ = zapExpectedType pat_ty `thenM` \ pat_ty' ->
+ unifyTauTy pat_ty' (hsLitType simple_lit) `thenM_`
+ returnM (LitPat simple_lit, emptyBag, emptyBag, [])
+
+tc_pat tc_bndr pat@(NPatIn over_lit mb_neg) pat_ty
+ = zapExpectedType pat_ty `thenM` \ pat_ty' ->
+ newOverloadedLit origin over_lit pat_ty' `thenM` \ pos_lit_expr ->
+ newMethodFromName origin pat_ty' eqName `thenM` \ eq ->
+ (case mb_neg of
+ Nothing -> returnM pos_lit_expr -- Positive literal
+ Just neg -> -- Negative literal
+ -- The 'negate' is re-mappable syntax
+ tcSyntaxName origin pat_ty' (negateName, noLoc (HsVar neg)) `thenM` \ (_, neg_expr) ->
+ returnM (mkHsApp neg_expr pos_lit_expr)
+ ) `thenM` \ lit_expr ->
-tcPat e (LitPatIn lit@(StringLit str))
- = getSrcLocTc `thenNF_Tc` \ loc ->
let
- origin = LiteralOrigin lit loc
- eq_id = lookupE_ClassOpByKey e eqClassKey SLIT("==")
+ -- The literal in an NPatIn is always positive...
+ -- But in NPat, the literal is used to find identical patterns
+ -- so we must negate the literal when necessary!
+ lit' = case (over_lit, mb_neg) of
+ (HsIntegral i _, Nothing) -> HsInteger i pat_ty'
+ (HsIntegral i _, Just _) -> HsInteger (-i) pat_ty'
+ (HsFractional f _, Nothing) -> HsRat f pat_ty'
+ (HsFractional f _, Just _) -> HsRat (-f) pat_ty'
in
- newMethod origin eq_id [stringTy] `thenNF_Tc` \ eq ->
- let
- comp_op = App (Var (mkInstId eq)) (Lit lit)
- in
- returnTc (NPat lit stringTy comp_op, mkLIE [eq], stringTy)
-
-{- OLD:
-tcPat e (LitPatIn lit@(StringLit str))
- = returnTc (NPat lit stringTy comp_op, nullLIE, stringTy)
+ returnM (NPatOut lit' pat_ty' (HsApp (nlHsVar eq) lit_expr),
+ emptyBag, emptyBag, [])
where
- comp_op = App (Var eqStringId) (Lit lit)
--}
-
-tcPat e (LitPatIn lit@(IntPrimLit _))
- = returnTc (LitPat lit intPrimTy, nullLIE, intPrimTy)
-tcPat e (LitPatIn lit@(CharPrimLit _))
- = returnTc (LitPat lit charPrimTy, nullLIE, charPrimTy)
-tcPat e (LitPatIn lit@(StringPrimLit _))
- = returnTc (LitPat lit addrPrimTy, nullLIE, addrPrimTy)
-tcPat e (LitPatIn lit@(FloatPrimLit _))
- = returnTc (LitPat lit floatPrimTy, nullLIE, floatPrimTy)
-tcPat e (LitPatIn lit@(DoublePrimLit _))
- = returnTc (LitPat lit doublePrimTy, nullLIE, doublePrimTy)
+ origin = PatOrigin pat
\end{code}
%************************************************************************
%* *
-\subsection{Overloaded patterns: int literals and \tr{n+k} patterns}
+\subsection{n+k patterns}
%* *
%************************************************************************
\begin{code}
-tcPat e (LitPatIn lit@(IntLit i))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- let
- origin = LiteralOrigin lit loc
- in
- newPolyTyVarTy `thenNF_Tc` \ tyvar_ty ->
- let
- from_int = lookupE_ClassOpByKey e numClassKey SLIT("fromInt")
- from_integer = lookupE_ClassOpByKey e numClassKey SLIT("fromInteger")
- eq_id = lookupE_ClassOpByKey e eqClassKey SLIT("==")
+tc_pat tc_bndr pat@(NPlusKPatIn (L nm_loc name) lit@(HsIntegral i _) minus_name) pat_ty
+ = addSrcSpan nm_loc (tc_bndr name pat_ty) `thenM` \ (co_fn, bndr_id) ->
+ let
+ pat_ty' = idType bndr_id
in
- newOverloadedLit origin
- (OverloadedIntegral i from_int from_integer)
- tyvar_ty `thenNF_Tc` \ over_lit ->
+ newOverloadedLit origin lit pat_ty' `thenM` \ over_lit_expr ->
+ newMethodFromName origin pat_ty' geName `thenM` \ ge ->
+
+ -- The '-' part is re-mappable syntax
+ tcSyntaxName origin pat_ty' (minusName, noLoc (HsVar minus_name)) `thenM` \ (_, minus_expr) ->
+
+ -- The Report says that n+k patterns must be in Integral
+ -- We may not want this when using re-mappable syntax, though (ToDo?)
+ tcLookupClass integralClassName `thenM` \ icls ->
+ newDicts origin [mkClassPred icls [pat_ty']] `thenM` \ dicts ->
+ extendLIEs dicts `thenM_`
+
+ returnM (NPlusKPatOut (L nm_loc bndr_id) i
+ (SectionR (nlHsVar ge) over_lit_expr)
+ (SectionR minus_expr over_lit_expr),
+ emptyBag, unitBag (name, bndr_id), [])
+ where
+ origin = PatOrigin pat
+\end{code}
- newMethod origin eq_id [tyvar_ty] `thenNF_Tc` \ eq ->
- returnTc (NPat lit tyvar_ty (App (Var (mkInstId eq))
- (Var (mkInstId over_lit))),
- mkLIE [over_lit, eq],
- tyvar_ty)
+%************************************************************************
+%* *
+\subsection{Lists of patterns}
+%* *
+%************************************************************************
-tcPat e (LitPatIn lit@(FracLit f))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- let
- origin = LiteralOrigin lit loc
- in
- newPolyTyVarTy `thenNF_Tc` \ tyvar_ty ->
- let
- eq_id = lookupE_ClassOpByKey e eqClassKey SLIT("==")
- from_rational = lookupE_ClassOpByKey e fractionalClassKey SLIT("fromRational")
- in
- newOverloadedLit origin
- (OverloadedFractional f from_rational)
- tyvar_ty `thenNF_Tc` \ over_lit ->
+Helper functions
- newMethod origin eq_id [tyvar_ty] `thenNF_Tc` \ eq ->
+\begin{code}
+tcPats :: BinderChecker -- How to deal with variables
+ -> [LPat Name] -> [TcType] -- Excess 'expected types' discarded
+ -> TcM ([LPat TcId],
+ Bag TcTyVar,
+ Bag (Name, TcId), -- Ids bound by the pattern
+ [Inst]) -- Dicts bound by the pattern
+
+tcPats tc_bndr [] tys = returnM ([], emptyBag, emptyBag, [])
+
+tcPats tc_bndr (pat:pats) (ty:tys)
+ = tcPat tc_bndr pat (Check ty) `thenM` \ (pat', tvs1, ids1, lie_avail1) ->
+ tcPats tc_bndr pats tys `thenM` \ (pats', tvs2, ids2, lie_avail2) ->
+
+ returnM (pat':pats',
+ tvs1 `unionBags` tvs2, ids1 `unionBags` ids2,
+ lie_avail1 ++ lie_avail2)
+\end{code}
- returnTc (NPat lit tyvar_ty (App (Var (mkInstId eq))
- (Var (mkInstId over_lit))),
- mkLIE [over_lit, eq],
- tyvar_ty)
-tcPat e (LitPatIn lit@(LitLitLitIn s))
- = error "tcPat: can't handle ``literal-literal'' patterns"
-{-
- = getSrcLocTc `thenNF_Tc` \ loc ->
- let
- origin = LiteralOrigin lit loc
- in
- newPolyTyVarTy `thenNF_Tc` \ tyvar_ty ->
- let
- eq_id = lookupE_ClassOpByKey e eqClassKey "=="
- in
- newOverloadedLit origin
- (OverloadedLitLit s)
- tyvar_ty `thenNF_Tc` \ over_lit ->
+%************************************************************************
+%* *
+\subsection{Constructor arguments}
+%* *
+%************************************************************************
- newMethod origin eq_id [tyvar_ty] `thenNF_Tc` \ eq ->
+\begin{code}
+tcConStuff tc_bndr data_con (PrefixCon arg_pats) arg_tys
+ = -- Check correct arity
+ checkTc (con_arity == no_of_args)
+ (arityErr "Constructor" data_con con_arity no_of_args) `thenM_`
- returnTc (NPat lit tyvar_ty (App (Var (mkInstId eq))
- (Var (mkInstId over_lit))),
- mkLIE [over_lit, eq],
- tyvar_ty)
--}
+ -- Check arguments
+ tcPats tc_bndr arg_pats arg_tys `thenM` \ (arg_pats', tvs, ids, lie_avail) ->
-tcPat e (NPlusKPatIn name lit@(IntLit k))
- = getSrcLocTc `thenNF_Tc` \ loc ->
- let
- origin = LiteralOrigin lit loc
+ returnM (PrefixCon arg_pats', tvs, ids, lie_avail)
+ where
+ con_arity = dataConSourceArity data_con
+ no_of_args = length arg_pats
- local = lookupE_Binder e name
- local_ty = getIdUniType local
+tcConStuff tc_bndr data_con (InfixCon p1 p2) arg_tys
+ = -- Check correct arity
+ checkTc (con_arity == 2)
+ (arityErr "Constructor" data_con con_arity 2) `thenM_`
- ge_id = lookupE_ClassOpByKey e ordClassKey SLIT(">=")
- minus_id = lookupE_ClassOpByKey e numClassKey SLIT("-")
- from_int = lookupE_ClassOpByKey e numClassKey SLIT("fromInt")
- from_integer = lookupE_ClassOpByKey e numClassKey SLIT("fromInteger")
- in
- newOverloadedLit origin
- (OverloadedIntegral k from_int from_integer)
- local_ty `thenNF_Tc` \ over_lit ->
-
- newMethod origin ge_id [local_ty] `thenNF_Tc` \ ge ->
- newMethod origin minus_id [local_ty] `thenNF_Tc` \ minus ->
-
- returnTc (NPlusKPat local lit local_ty
- (Var (mkInstId over_lit))
- (Var (mkInstId ge))
- (Var (mkInstId minus)),
- mkLIE [over_lit, ge, minus],
- local_ty)
-
-tcPat e (NPlusKPatIn pat other) = panic "TcPat:NPlusKPat: not an IntLit"
-
-#ifdef DPH
-tcPat e (ProcessorPatIn pats pat)
- = tcPidPats e pats `thenTc` \ (pats',convs, lie, tys)->
- tcPat e pat `thenTc` \ (pat', ty, lie') ->
- returnTc (ProcessorPat pats' convs pat',
- plusLIE lie lie',
- mkProcessorTy tys ty)
-#endif {- Data Parallel Haskell -}
+ -- Check arguments
+ tcPat tc_bndr p1 (Check ty1) `thenM` \ (p1', tvs1, ids1, lie_avail1) ->
+ tcPat tc_bndr p2 (Check ty2) `thenM` \ (p2', tvs2, ids2, lie_avail2) ->
+
+ returnM (InfixCon p1' p2',
+ tvs1 `unionBags` tvs2, ids1 `unionBags` ids2,
+ lie_avail1 ++ lie_avail2)
+ where
+ con_arity = dataConSourceArity data_con
+ [ty1, ty2] = arg_tys
+
+tcConStuff tc_bndr data_con (RecCon rpats) arg_tys
+ = -- Check the fields
+ tc_fields field_tys rpats `thenM` \ (rpats', tvs, ids, lie_avail) ->
+ returnM (RecCon rpats', tvs, ids, lie_avail)
+
+ where
+ field_tys = zip (map fieldLabelName (dataConFieldLabels data_con)) arg_tys
+ -- Don't use zipEqual! If the constructor isn't really a record, then
+ -- dataConFieldLabels will be empty (and each field in the pattern
+ -- will generate an error below).
+
+ tc_fields field_tys []
+ = returnM ([], emptyBag, emptyBag, [])
+
+ tc_fields field_tys ((L lbl_loc field_label, rhs_pat) : rpats)
+ = tc_fields field_tys rpats `thenM` \ (rpats', tvs1, ids1, lie_avail1) ->
+
+ (case [ty | (f,ty) <- field_tys, f == field_label] of
+
+ -- No matching field; chances are this field label comes from some
+ -- other record type (or maybe none). As well as reporting an
+ -- error we still want to typecheck the pattern, principally to
+ -- make sure that all the variables it binds are put into the
+ -- environment, else the type checker crashes later:
+ -- f (R { foo = (a,b) }) = a+b
+ -- If foo isn't one of R's fields, we don't want to crash when
+ -- typechecking the "a+b".
+ [] -> addErrTc (badFieldCon data_con field_label) `thenM_`
+ newTyVarTy liftedTypeKind `thenM` \ bogus_ty ->
+ returnM (error "Bogus selector Id", bogus_ty)
+
+ -- The normal case, when the field comes from the right constructor
+ (pat_ty : extras) ->
+ ASSERT( null extras )
+ addSrcSpan lbl_loc (tcLookupId field_label) `thenM` \ sel_id ->
+ returnM (sel_id, pat_ty)
+ ) `thenM` \ (sel_id, pat_ty) ->
+
+ tcPat tc_bndr rhs_pat (Check pat_ty) `thenM` \ (rhs_pat', tvs2, ids2, lie_avail2) ->
+
+ returnM ((L lbl_loc sel_id, rhs_pat') : rpats',
+ tvs1 `unionBags` tvs2,
+ ids1 `unionBags` ids2,
+ lie_avail1 ++ lie_avail2)
\end{code}
+
%************************************************************************
%* *
-\subsection{Lists of patterns}
+\subsection{Subsumption}
%* *
%************************************************************************
+Example:
+ f :: (forall a. a->a) -> Int -> Int
+ f (g::Int->Int) y = g y
+This is ok: the type signature allows fewer callers than
+the (more general) signature f :: (Int->Int) -> Int -> Int
+I.e. (forall a. a->a) <= Int -> Int
+We end up translating this to:
+ f = \g' :: (forall a. a->a). let g = g' Int in g' y
+
+tcSubPat does the work
+ sig_ty is the signature on the pattern itself
+ (Int->Int in the example)
+ expected_ty is the type passed inwards from the context
+ (forall a. a->a in the example)
+
\begin{code}
-tcPats :: E -> [RenamedPat] -> TcM ([TypecheckedPat], LIE, [UniType])
+tcSubPat :: TcSigmaType -> Expected TcSigmaType -> TcM PatCoFn
+
+tcSubPat sig_ty exp_ty
+ = tcSubOff sig_ty exp_ty `thenM` \ co_fn ->
+ -- co_fn is a coercion on *expressions*, and we
+ -- need to make a coercion on *patterns*
+ if isIdCoercion co_fn then
+ returnM idCoercion
+ else
+ newUnique `thenM` \ uniq ->
+ readExpectedType exp_ty `thenM` \ exp_ty' ->
+ let
+ arg_id = mkSysLocal FSLIT("sub") uniq exp_ty'
+ the_fn = DictLam [arg_id] (noLoc (co_fn <$> HsVar arg_id))
+ pat_co_fn p = SigPatOut (noLoc p) exp_ty' the_fn
+ in
+ returnM (mkCoercion pat_co_fn)
+\end{code}
-tcPats e [] = returnTc ([], nullLIE, [])
-tcPats e (pat:pats)
- = tcPat e pat `thenTc` \ (pat', lie, ty) ->
- tcPats e pats `thenTc` \ (pats', lie', tys) ->
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
- returnTc (pat':pats', plusLIE lie lie', ty:tys)
-\end{code}
+\begin{code}
+patCtxt pat = hang (ptext SLIT("When checking the pattern:"))
+ 4 (ppr pat)
-@matchConArgTys@ grabs the signature of the data constructor, and
-unifies the actual args against the expected ones.
+badFieldCon :: DataCon -> Name -> SDoc
+badFieldCon con field
+ = hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
+ ptext SLIT("does not have field"), quotes (ppr field)]
-\begin{code}
-matchConArgTys :: Id -> [UniType] -> (UniType -> UnifyErrContext) -> TcM UniType
-
-matchConArgTys con_id arg_tys err_ctxt
- = let
- no_of_args = length arg_tys
- (sig_tyvars, sig_theta, sig_tys, _) = getDataConSig con_id
- -- Ignore the sig_theta; overloaded constructors only
- -- behave differently when called, not when used for
- -- matching.
- con_arity = length sig_tys
- in
- getSrcLocTc `thenNF_Tc` \ loc ->
- checkTc (con_arity /= no_of_args)
- (dataConArityErr con_id con_arity no_of_args loc) `thenTc_`
+polyPatSig :: TcType -> SDoc
+polyPatSig sig_ty
+ = hang (ptext SLIT("Illegal polymorphic type signature in pattern:"))
+ 4 (ppr sig_ty)
- copyTyVars sig_tyvars `thenNF_Tc` \ (inst_env, _, new_tyvar_tys) ->
- let
- (_,inst_arg_tys,inst_result_ty) = getInstantiatedDataConSig con_id new_tyvar_tys
- in
- unifyTauTyLists arg_tys inst_arg_tys (err_ctxt inst_result_ty) `thenTc_`
- returnTc inst_result_ty
+badTypePat pat = ptext SLIT("Illegal type pattern") <+> ppr pat
\end{code}
+
projects / ghc-hetmet.git / blobdiff