%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcPat]{Typechecking patterns}
\begin{code}
-module TcPat ( tcPat, badFieldsCon ) where
+module TcPat ( tcPat, tcVarPat, badFieldCon ) where
#include "HsVersions.h"
-import HsSyn ( InPat(..), OutPat(..), HsLit(..), HsExpr(..) )
+import HsSyn ( InPat(..), OutPat(..), HsLit(..), HsExpr(..), Sig(..) )
import RnHsSyn ( RenamedPat )
-import TcHsSyn ( TcPat )
+import TcHsSyn ( TcPat, TcIdBndr )
import TcMonad
import Inst ( Inst, OverloadedLit(..), InstOrigin(..),
- emptyLIE, plusLIE, plusLIEs, LIE,
- newMethod, newOverloadedLit
+ emptyLIE, plusLIE, LIE,
+ newMethod, newMethodWithGivenTy, newOverloadedLit,
+ newDicts, instToIdBndr
)
-import Name ( Name {- instance Outputable -} )
-import TcEnv ( TcIdOcc(..), tcLookupGlobalValue, tcLookupGlobalValueByKey,
- tcLookupLocalValueOK, tcInstId
- )
-import TcType ( TcType, TcMaybe, newTyVarTy, newTyVarTys )
+import Name ( Name, getOccName, getSrcLoc )
import FieldLabel ( fieldLabelName )
-import Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists )
+import TcEnv ( TcIdOcc(..), tcLookupGlobalValue,
+ tcLookupGlobalValueByKey, newLocalId, badCon
+ )
+import TcType ( TcType, TcTyVar, tcInstTyVars )
+import TcUnify ( unifyTauTy, unifyListTy,
+ unifyTupleTy, unifyUnboxedTupleTy
+ )
-import Maybes ( maybeToBool )
import Bag ( Bag )
import CmdLineOpts ( opt_IrrefutableTuples )
-import Id ( GenId, idType, Id, dataConFieldLabels )
-import Kind ( Kind, mkBoxedTypeKind, mkTypeKind )
-import Type ( splitFunTys, splitRhoTy,
- splitFunTy_maybe, splitAlgTyConApp_maybe,
- Type
- )
+import DataCon ( DataCon, dataConSig, dataConFieldLabels, dataConSourceArity )
+import Id ( Id, idType, isDataConId_maybe )
+import Type ( Type, substFlexiTy, substFlexiTheta, mkTyConApp )
import TysPrim ( charPrimTy, intPrimTy, floatPrimTy,
doublePrimTy, addrPrimTy
)
-import TysWiredIn ( charTy, stringTy, mkListTy, mkTupleTy, intTy )
-import Unique ( Unique, eqClassOpKey, geClassOpKey, minusClassOpKey )
-import Util ( assertPanic, panic )
+import TysWiredIn ( charTy, stringTy, intTy )
+import SrcLoc ( SrcLoc )
+import Unique ( eqClassOpKey, geClassOpKey, minusClassOpKey )
+import Bag
+import Util ( zipEqual )
import Outputable
\end{code}
+
+%************************************************************************
+%* *
+\subsection{Variable patterns}
+%* *
+%************************************************************************
+
+\begin{code}
+tcVarPat :: (Name -> Maybe (TcIdBndr s)) -- Info about signatures
+ -> Name
+ -> TcType s -- Expected type
+ -> TcM s (TcIdBndr s) -- The monomorphic Id; this is put in the pattern itself
+
+tcVarPat sig_fn binder_name pat_ty
+ = case sig_fn binder_name of
+ Nothing -> newLocalId (getOccName binder_name) pat_ty `thenNF_Tc` \ bndr_id ->
+ returnTc bndr_id
+
+ Just bndr_id -> tcAddSrcLoc (getSrcLoc binder_name) $
+ unifyTauTy pat_ty (idType bndr_id) `thenTc_`
+ returnTc bndr_id
+\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Typechecking patterns}
+%* *
+%************************************************************************
+
\begin{code}
-tcPat :: RenamedPat -> TcM s (TcPat s, LIE s, TcType s)
+tcPat :: (Name -> Maybe (TcIdBndr s)) -- Info about signatures
+ -> RenamedPat
+ -> TcType s -- Expected type
+ -> TcM s (TcPat s,
+ LIE s, -- Required by n+k and literal pats
+ Bag (TcTyVar s), -- TyVars bound by the pattern
+ Bag (Name, TcIdBndr s), -- 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.
+ LIE s) -- Dicts or methods [see below] bound by the pattern
\end{code}
+
%************************************************************************
%* *
\subsection{Variables, wildcards, lazy pats, as-pats}
%************************************************************************
\begin{code}
-tcPat (VarPatIn name)
- = tcLookupLocalValueOK "tcPat1:" name `thenNF_Tc` \ id ->
- returnTc (VarPat (TcId id), emptyLIE, idType id)
+tcPat sig_fn (VarPatIn name) pat_ty
+ = tcVarPat sig_fn name pat_ty `thenTc` \ bndr_id ->
+ returnTc (VarPat (TcId bndr_id), emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
-tcPat (LazyPatIn pat)
- = tcPat pat `thenTc` \ (pat', lie, ty) ->
- returnTc (LazyPat pat', lie, ty)
+tcPat sig_fn (LazyPatIn pat) pat_ty
+ = tcPat sig_fn pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
+ returnTc (LazyPat pat', lie_req, tvs, ids, lie_avail)
-tcPat pat_in@(AsPatIn name pat)
- = tcLookupLocalValueOK "tcPat2" name `thenNF_Tc` \ id ->
- tcPat pat `thenTc` \ (pat', lie, ty) ->
+tcPat sig_fn pat_in@(AsPatIn name pat) pat_ty
+ = tcVarPat sig_fn name pat_ty `thenTc` \ bndr_id ->
+ tcPat sig_fn pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
tcAddErrCtxt (patCtxt pat_in) $
- unifyTauTy (idType id) ty `thenTc_`
- returnTc (AsPat (TcId id) pat', lie, ty)
+ returnTc (AsPat (TcId bndr_id) pat', lie_req,
+ tvs, (name, bndr_id) `consBag` ids,
+ lie_avail)
-tcPat WildPatIn
- = newTyVarTy mkTypeKind `thenNF_Tc` \ tyvar_ty ->
- returnTc (WildPat tyvar_ty, emptyLIE, tyvar_ty)
+tcPat sig_fn WildPatIn pat_ty
+ = returnTc (WildPat pat_ty, emptyLIE, emptyBag, emptyBag, emptyLIE)
-tcPat (NegPatIn pat)
- = tcPat (negate_lit pat)
+tcPat sig_fn (NegPatIn pat) pat_ty
+ = tcPat sig_fn (negate_lit pat) pat_ty
where
negate_lit (LitPatIn (HsInt i)) = LitPatIn (HsInt (-i))
negate_lit (LitPatIn (HsFrac f)) = LitPatIn (HsFrac (-f))
negate_lit _ = panic "TcPat:negate_pat"
-tcPat (ParPatIn parend_pat)
- = tcPat parend_pat
+tcPat sig_fn (ParPatIn parend_pat) pat_ty
+ = tcPat sig_fn parend_pat pat_ty
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcPat pat_in@(ListPatIn pats)
- = tcPats pats `thenTc` \ (pats', lie, tys) ->
- newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- tcAddErrCtxt (patCtxt pat_in) $
- unifyTauTyList (tyvar_ty:tys) `thenTc_`
+tcPat sig_fn pat_in@(ListPatIn pats) pat_ty
+ = tcAddErrCtxt (patCtxt pat_in) $
+ unifyListTy pat_ty `thenTc` \ elem_ty ->
+ tcPats sig_fn pats (repeat elem_ty) `thenTc` \ (pats', lie_req, tvs, ids, lie_avail) ->
+ returnTc (ListPat elem_ty pats', lie_req, tvs, ids, lie_avail)
- returnTc (ListPat tyvar_ty pats', lie, mkListTy tyvar_ty)
+tcPat sig_fn pat_in@(TuplePatIn pats boxed) pat_ty
+ = tcAddErrCtxt (patCtxt pat_in) $
-tcPat pat_in@(TuplePatIn pats)
- = let
- arity = length pats
- in
- tcPats pats `thenTc` \ (pats', lie, tys) ->
-
- -- Make sure we record that the tuples can only contain boxed types
- newTyVarTys arity mkBoxedTypeKind `thenNF_Tc` \ tyvar_tys ->
+ (if boxed
+ then unifyTupleTy arity pat_ty
+ else unifyUnboxedTupleTy arity pat_ty) `thenTc` \ arg_tys ->
- tcAddErrCtxt (patCtxt pat_in) $
- unifyTauTyLists tyvar_tys tys `thenTc_`
+ tcPats sig_fn pats arg_tys `thenTc` \ (pats', lie_req, tvs, ids, lie_avail) ->
-- possibly do the "make all tuple-pats irrefutable" test:
let
- unmangled_result = TuplePat pats'
+ unmangled_result = TuplePat pats' boxed
-- Under flag control turn a pattern (x,y,z) into ~(x,y,z)
-- so that we can experiment with lazy tuple-matching.
-- it was easy to do.
possibly_mangled_result
- = if opt_IrrefutableTuples
- then LazyPat unmangled_result
- else unmangled_result
-
- -- ToDo: IrrefutableEverything
+ | opt_IrrefutableTuples && boxed = LazyPat unmangled_result
+ | otherwise = unmangled_result
in
- returnTc (possibly_mangled_result, lie, mkTupleTy arity tys)
+ returnTc (possibly_mangled_result, lie_req, 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 pat_in@(ConPatIn name pats)
- = tcPats pats `thenTc` \ (pats', lie, tys) ->
-
- tcAddErrCtxt (patCtxt pat_in) $
- matchConArgTys name tys `thenTc` \ (con_id, data_ty) ->
-
- returnTc (ConPat con_id data_ty pats',
- lie,
- data_ty)
-
-tcPat pat_in@(ConOpPatIn pat1 op _ pat2) -- in binary-op form...
- = tcPat pat1 `thenTc` \ (pat1', lie1, ty1) ->
- tcPat pat2 `thenTc` \ (pat2', lie2, ty2) ->
-
- tcAddErrCtxt (patCtxt pat_in) $
- matchConArgTys op [ty1,ty2] `thenTc` \ (con_id, data_ty) ->
+tcPat sig_fn pat@(ConPatIn name arg_pats) pat_ty
+ = tcConPat sig_fn pat name arg_pats pat_ty
- returnTc (ConOpPat pat1' con_id pat2' data_ty,
- lie1 `plusLIE` lie2,
- data_ty)
+tcPat sig_fn pat@(ConOpPatIn pat1 op _ pat2) pat_ty
+ = tcConPat sig_fn pat op [pat1, pat2] pat_ty
\end{code}
+
%************************************************************************
%* *
\subsection{Records}
%************************************************************************
\begin{code}
-tcPat pat_in@(RecPatIn name rpats)
- = tcLookupGlobalValue name `thenNF_Tc` \ con_id ->
- tcInstId con_id `thenNF_Tc` \ (_, _, con_tau) ->
- let
- -- Ignore the con_theta; overloaded constructors only
- -- behave differently when called, not when used for
- -- matching.
- (_, record_ty) = splitFunTys con_tau
+tcPat sig_fn pat@(RecPatIn name rpats) pat_ty
+ = tcAddErrCtxt (patCtxt pat) $
- field_names = map fieldLabelName (dataConFieldLabels con_id)
- bad_fields = [f | (f,_,_) <- rpats, not (f `elem` field_names)]
+ -- Check the constructor itself
+ tcConstructor pat name pat_ty `thenTc` \ (data_con, ex_tvs, dicts, lie_avail1, arg_tys) ->
+ let
+ field_tys = zipEqual "tcPat"
+ (map fieldLabelName (dataConFieldLabels data_con))
+ arg_tys
in
- -- Check that all the fields are from this constructor
- checkTc (null bad_fields) (badFieldsCon name bad_fields) `thenTc_`
-
- -- Con is syntactically constrained to be a data constructor
- ASSERT( maybeToBool (splitAlgTyConApp_maybe record_ty) )
- mapAndUnzipTc (do_bind record_ty) rpats `thenTc` \ (rpats', lies) ->
+ -- Check the fields
+ tc_fields field_tys rpats `thenTc` \ (rpats', lie_req, tvs, ids, lie_avail2) ->
- returnTc (RecPat con_id record_ty rpats',
- plusLIEs lies,
- record_ty)
+ returnTc (RecPat data_con pat_ty ex_tvs dicts rpats',
+ lie_req,
+ listToBag ex_tvs `unionBags` tvs,
+ ids,
+ lie_avail1 `plusLIE` lie_avail2)
where
- do_bind expected_record_ty (field_label, rhs_pat, pun_flag)
- = tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
- tcInstId sel_id `thenNF_Tc` \ (_, _, tau) ->
-
- -- Record selectors all have type
- -- forall a1..an. T a1 .. an -> tau
- ASSERT( maybeToBool (splitFunTy_maybe tau) )
- let
- -- Selector must have type RecordType -> FieldType
- Just (record_ty, field_ty) = splitFunTy_maybe tau
- in
- tcAddErrCtxt (recordLabel field_label) (
- unifyTauTy expected_record_ty record_ty
- ) `thenTc_`
- tcPat rhs_pat `thenTc` \ (rhs_pat', lie, rhs_ty) ->
- tcAddErrCtxt (recordRhs field_label rhs_pat) (
- unifyTauTy field_ty rhs_ty
- ) `thenTc_`
- returnTc ((sel_id, rhs_pat', pun_flag), lie)
+ tc_fields field_tys []
+ = returnTc ([], emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+ tc_fields field_tys ((field_label, rhs_pat, pun_flag) : rpats)
+ | null matching_fields
+ = addErrTc (badFieldCon name field_label) `thenNF_Tc_`
+ tc_fields field_tys rpats
+
+ | otherwise
+ = ASSERT( null extras )
+ tc_fields field_tys rpats `thenTc` \ (rpats', lie_req1, tvs1, ids1, lie_avail1) ->
+
+ tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
+ tcPat sig_fn rhs_pat rhs_ty `thenTc` \ (rhs_pat', lie_req2, tvs2, ids2, lie_avail2) ->
+
+ returnTc ((sel_id, rhs_pat', pun_flag) : rpats',
+ lie_req1 `plusLIE` lie_req2,
+ tvs1 `unionBags` tvs2,
+ ids1 `unionBags` ids2,
+ lie_avail1 `plusLIE` lie_avail2)
+ where
+ matching_fields = [ty | (f,ty) <- field_tys, f == field_label]
+ (rhs_ty : extras) = matching_fields
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcPat (LitPatIn lit@(HsChar str))
- = returnTc (LitPat lit charTy, emptyLIE, charTy)
-
-tcPat (LitPatIn lit@(HsString str))
- = tcLookupGlobalValueByKey eqClassOpKey `thenNF_Tc` \ sel_id ->
- newMethod (LiteralOrigin lit)
- (RealId sel_id) [stringTy] `thenNF_Tc` \ (lie, eq_id) ->
- let
- comp_op = HsApp (HsVar eq_id) (HsLitOut lit stringTy)
- in
- returnTc (NPat lit stringTy comp_op, lie, stringTy)
-
-tcPat (LitPatIn lit@(HsIntPrim _))
- = returnTc (LitPat lit intPrimTy, emptyLIE, intPrimTy)
-tcPat (LitPatIn lit@(HsCharPrim _))
- = returnTc (LitPat lit charPrimTy, emptyLIE, charPrimTy)
-tcPat (LitPatIn lit@(HsStringPrim _))
- = returnTc (LitPat lit addrPrimTy, emptyLIE, addrPrimTy)
-tcPat (LitPatIn lit@(HsFloatPrim _))
- = returnTc (LitPat lit floatPrimTy, emptyLIE, floatPrimTy)
-tcPat (LitPatIn lit@(HsDoublePrim _))
- = returnTc (LitPat lit doublePrimTy, emptyLIE, doublePrimTy)
+tcPat sig_fn (LitPatIn lit@(HsChar _)) pat_ty = tcSimpleLitPat lit charTy pat_ty
+tcPat sig_fn (LitPatIn lit@(HsIntPrim _)) pat_ty = tcSimpleLitPat lit intPrimTy pat_ty
+tcPat sig_fn (LitPatIn lit@(HsCharPrim _)) pat_ty = tcSimpleLitPat lit charPrimTy pat_ty
+tcPat sig_fn (LitPatIn lit@(HsStringPrim _)) pat_ty = tcSimpleLitPat lit addrPrimTy pat_ty
+tcPat sig_fn (LitPatIn lit@(HsFloatPrim _)) pat_ty = tcSimpleLitPat lit floatPrimTy pat_ty
+tcPat sig_fn (LitPatIn lit@(HsDoublePrim _)) pat_ty = tcSimpleLitPat lit doublePrimTy pat_ty
+
+tcPat sig_fn (LitPatIn lit@(HsLitLit s)) pat_ty = tcSimpleLitPat lit intTy pat_ty
+ -- This one looks weird!
\end{code}
%************************************************************************
%************************************************************************
\begin{code}
-tcPat (LitPatIn lit@(HsInt i))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- newOverloadedLit origin
- (OverloadedIntegral i) tyvar_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
-
- tcLookupGlobalValueByKey eqClassOpKey `thenNF_Tc` \ eq_sel_id ->
- newMethod origin (RealId eq_sel_id) [tyvar_ty] `thenNF_Tc` \ (lie2, eq_id) ->
-
- returnTc (NPat lit tyvar_ty (HsApp (HsVar eq_id)
- over_lit_expr),
- lie1 `plusLIE` lie2,
- tyvar_ty)
- where
- origin = LiteralOrigin lit
+tcPat sig_fn pat@(LitPatIn lit@(HsString str)) pat_ty
+ = unifyTauTy pat_ty stringTy `thenTc_`
+ tcLookupGlobalValueByKey eqClassOpKey `thenNF_Tc` \ sel_id ->
+ newMethod (PatOrigin pat)
+ (RealId sel_id) [stringTy] `thenNF_Tc` \ (lie, eq_id) ->
+ let
+ comp_op = HsApp (HsVar eq_id) (HsLitOut lit stringTy)
+ in
+ returnTc (NPat lit stringTy comp_op, lie, emptyBag, emptyBag, emptyLIE)
-tcPat (LitPatIn lit@(HsFrac f))
- = newTyVarTy mkBoxedTypeKind `thenNF_Tc` \ tyvar_ty ->
- newOverloadedLit origin
- (OverloadedFractional f) tyvar_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
- tcLookupGlobalValueByKey eqClassOpKey `thenNF_Tc` \ eq_sel_id ->
- newMethod origin (RealId eq_sel_id) [tyvar_ty] `thenNF_Tc` \ (lie2, eq_id) ->
+tcPat sig_fn pat@(LitPatIn lit@(HsInt i)) pat_ty
+ = tcOverloadedLitPat pat lit (OverloadedIntegral i) pat_ty
- returnTc (NPat lit tyvar_ty (HsApp (HsVar eq_id)
- over_lit_expr),
- lie1 `plusLIE` lie2,
- tyvar_ty)
- where
- origin = LiteralOrigin lit
+tcPat sig_fn pat@(LitPatIn lit@(HsFrac f)) pat_ty
+ = tcOverloadedLitPat pat lit (OverloadedFractional f) pat_ty
-tcPat (LitPatIn lit@(HsLitLit s))
--- = error "tcPat: can't handle ``literal-literal'' patterns"
- = returnTc (LitPat lit intTy, emptyLIE, intTy)
-tcPat (NPlusKPatIn name lit@(HsInt i))
- = tcLookupLocalValueOK "tcPat1:n+k" name `thenNF_Tc` \ local ->
- let
- local_ty = idType local
- in
+tcPat sig_fn pat@(NPlusKPatIn name lit@(HsInt i)) pat_ty
+ = tcVarPat sig_fn name pat_ty `thenTc` \ bndr_id ->
tcLookupGlobalValueByKey geClassOpKey `thenNF_Tc` \ ge_sel_id ->
tcLookupGlobalValueByKey minusClassOpKey `thenNF_Tc` \ minus_sel_id ->
newOverloadedLit origin
- (OverloadedIntegral i) local_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
+ (OverloadedIntegral i) pat_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
- newMethod origin (RealId ge_sel_id) [local_ty] `thenNF_Tc` \ (lie2, ge_id) ->
- newMethod origin (RealId minus_sel_id) [local_ty] `thenNF_Tc` \ (lie3, minus_id) ->
+ newMethod origin (RealId ge_sel_id) [pat_ty] `thenNF_Tc` \ (lie2, ge_id) ->
+ newMethod origin (RealId minus_sel_id) [pat_ty] `thenNF_Tc` \ (lie3, minus_id) ->
- returnTc (NPlusKPat (TcId local) lit local_ty
+ returnTc (NPlusKPat (TcId bndr_id) lit pat_ty
(SectionR (HsVar ge_id) over_lit_expr)
(SectionR (HsVar minus_id) over_lit_expr),
lie1 `plusLIE` lie2 `plusLIE` lie3,
- local_ty)
+ emptyBag, unitBag (name, bndr_id), emptyLIE)
where
- origin = LiteralOrigin lit -- Not very good!
+ origin = PatOrigin pat
-tcPat (NPlusKPatIn pat other) = panic "TcPat:NPlusKPat: not an HsInt literal"
+tcPat sig_fn (NPlusKPatIn pat other) pat_ty
+ = panic "TcPat:NPlusKPat: not an HsInt literal"
\end{code}
%************************************************************************
%* *
%************************************************************************
+Helper functions
+
\begin{code}
-tcPats :: [RenamedPat] -> TcM s ([TcPat s], LIE s, [TcType s])
+tcPats :: (Name -> Maybe (TcIdBndr s)) -- Info about signatures
+ -> [RenamedPat] -> [TcType s] -- Excess 'expected types' discarded
+ -> TcM s ([TcPat s],
+ LIE s, -- Required by n+k and literal pats
+ Bag (TcTyVar s),
+ Bag (Name, TcIdBndr s), -- Ids bound by the pattern
+ LIE s) -- Dicts bound by the pattern
+
+tcPats sig_fn [] tys = returnTc ([], emptyLIE, emptyBag, emptyBag, emptyLIE)
+
+tcPats sig_fn (ty:tys) (pat:pats)
+ = tcPat sig_fn ty pat `thenTc` \ (pat', lie_req1, tvs1, ids1, lie_avail1) ->
+ tcPats sig_fn tys pats `thenTc` \ (pats', lie_req2, tvs2, ids2, lie_avail2) ->
+
+ returnTc (pat':pats', lie_req1 `plusLIE` lie_req2,
+ tvs1 `unionBags` tvs2, ids1 `unionBags` ids2,
+ lie_avail1 `plusLIE` lie_avail2)
+\end{code}
-tcPats [] = returnTc ([], emptyLIE, [])
+------------------------------------------------------
+\begin{code}
+tcSimpleLitPat lit lit_ty pat_ty
+ = unifyTauTy pat_ty lit_ty `thenTc_`
+ returnTc (LitPat lit lit_ty, emptyLIE, emptyBag, emptyBag, emptyLIE)
-tcPats (pat:pats)
- = tcPat pat `thenTc` \ (pat', lie, ty) ->
- tcPats pats `thenTc` \ (pats', lie', tys) ->
- returnTc (pat':pats', plusLIE lie lie', ty:tys)
-\end{code}
+tcOverloadedLitPat pat lit over_lit pat_ty
+ = newOverloadedLit (PatOrigin pat) over_lit pat_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
+ tcLookupGlobalValueByKey eqClassOpKey `thenNF_Tc` \ eq_sel_id ->
+ newMethod origin (RealId eq_sel_id) [pat_ty] `thenNF_Tc` \ (lie2, eq_id) ->
-@matchConArgTys@ grabs the signature of the data constructor, and
-unifies the actual args against the expected ones.
+ returnTc (NPat lit pat_ty (HsApp (HsVar eq_id)
+ over_lit_expr),
+ lie1 `plusLIE` lie2,
+ emptyBag, emptyBag, emptyLIE)
+ where
+ origin = PatOrigin pat
+\end{code}
+------------------------------------------------------
\begin{code}
-matchConArgTys :: Name -> [TcType s] -> TcM s (Id, TcType s)
-
-matchConArgTys con arg_tys
- = tcLookupGlobalValue con `thenNF_Tc` \ con_id ->
- tcInstId con_id `thenNF_Tc` \ (_, _, con_tau) ->
- -- Ignore the con_theta; overloaded constructors only
+tcConstructor pat con_name pat_ty
+ = -- Check that it's a constructor
+ tcLookupGlobalValue con_name `thenNF_Tc` \ con_id ->
+ case isDataConId_maybe con_id of {
+ Nothing -> failWithTc (badCon con_id);
+ Just data_con ->
+
+ -- Instantiate it
+ let
+ (tvs, theta, ex_tvs, ex_theta, arg_tys, tycon) = dataConSig data_con
+ -- Ignore the theta; overloaded constructors only
-- behave differently when called, not when used for
-- matching.
+ in
+ tcInstTyVars (ex_tvs ++ tvs) `thenNF_Tc` \ (all_tvs', ty_args', tenv) ->
+ let
+ ex_theta' = substFlexiTheta tenv ex_theta
+ arg_tys' = map (substFlexiTy tenv) arg_tys
+
+ n_ex_tvs = length ex_tvs
+ ex_tvs' = take n_ex_tvs all_tvs'
+ result_ty = mkTyConApp tycon (drop n_ex_tvs ty_args')
+ in
+ newDicts (PatOrigin pat) ex_theta' `thenNF_Tc` \ (lie_avail, dicts) ->
+
+ -- Check overall type matches
+ unifyTauTy pat_ty result_ty `thenTc_`
+
+ returnTc (data_con, ex_tvs', dicts, lie_avail, arg_tys')
+ }
+\end{code}
+
+------------------------------------------------------
+\begin{code}
+tcConPat sig_fn pat con_name arg_pats pat_ty
+ = tcAddErrCtxt (patCtxt pat) $
+
+ -- Check the constructor itself
+ tcConstructor pat con_name pat_ty `thenTc` \ (data_con, ex_tvs', dicts, lie_avail1, arg_tys') ->
+
+ -- Check correct arity
let
- (con_args, con_result) = splitFunTys con_tau
- con_arity = length con_args
- no_of_args = length arg_tys
+ con_arity = dataConSourceArity data_con
+ no_of_args = length arg_pats
in
checkTc (con_arity == no_of_args)
- (arityErr "Constructor" con_id con_arity no_of_args) `thenTc_`
+ (arityErr "Constructor" data_con con_arity no_of_args) `thenTc_`
+
+ -- Check arguments
+ tcPats sig_fn arg_pats arg_tys' `thenTc` \ (arg_pats', lie_req, tvs, ids, lie_avail2) ->
- unifyTauTyLists con_args arg_tys `thenTc_`
- returnTc (con_id, con_result)
+ returnTc (ConPat data_con pat_ty ex_tvs' dicts arg_pats',
+ lie_req,
+ listToBag ex_tvs' `unionBags` tvs,
+ ids,
+ lie_avail1 `plusLIE` lie_avail2)
\end{code}
-% =================================================
-Errors and contexts
-~~~~~~~~~~~~~~~~~~~
+%************************************************************************
+%* *
+\subsection{Errors and contexts}
+%* *
+%************************************************************************
+
\begin{code}
patCtxt pat = hang (ptext SLIT("In the pattern:"))
4 (ppr pat)
= hang (ptext SLIT("In the record field pattern"))
4 (sep [ppr field_label, char '=', ppr pat])
-badFieldsCon :: Name -> [Name] -> SDoc
-badFieldsCon con fields
+badFieldCon :: Name -> Name -> SDoc
+badFieldCon con field
= hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
- ptext SLIT("does not have field(s):"), pprQuotedList fields]
+ ptext SLIT("does not have field"), quotes (ppr field)]
\end{code}
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