\section[TcPat]{Typechecking patterns}
\begin{code}
-module TcPat ( tcPat, tcVarPat, badFieldCon ) where
+module TcPat ( tcPat, tcVarPat, badFieldCon, polyPatSig ) where
#include "HsVersions.h"
+import {-# SOURCE #-} TcExpr( tcExpr )
+
import HsSyn ( InPat(..), OutPat(..), HsLit(..), HsExpr(..), Sig(..) )
import RnHsSyn ( RenamedPat )
-import TcHsSyn ( TcPat, TcIdBndr )
+import TcHsSyn ( TcPat, TcId )
import TcMonad
import Inst ( Inst, OverloadedLit(..), InstOrigin(..),
)
import Name ( Name, getOccName, getSrcLoc )
import FieldLabel ( fieldLabelName )
-import TcEnv ( TcIdOcc(..), tcLookupGlobalValue,
- tcLookupGlobalValueByKey, newLocalId, badCon
+import TcEnv ( tcLookupValue,
+ tcLookupValueByKey, newLocalId, badCon
)
import TcType ( TcType, TcTyVar, tcInstTyVars )
+import TcMonoType ( tcHsType )
import TcUnify ( unifyTauTy, unifyListTy,
unifyTupleTy, unifyUnboxedTupleTy
)
import Bag ( Bag )
import CmdLineOpts ( opt_IrrefutableTuples )
import DataCon ( DataCon, dataConSig, dataConFieldLabels, dataConSourceArity )
-import Id ( Id, idType, isDataConId_maybe )
-import Type ( Type, substFlexiTy, substFlexiTheta, mkTyConApp )
+import Id ( Id, mkUserId, idType, isDataConId_maybe )
+import Type ( Type, isTauTy, substTopTy, substTopTheta, mkTyConApp )
import TysPrim ( charPrimTy, intPrimTy, floatPrimTy,
doublePrimTy, addrPrimTy
)
%************************************************************************
\begin{code}
-tcVarPat :: (Name -> Maybe (TcIdBndr s)) -- Info about signatures
+tcVarPat :: (Name -> Maybe TcId) -- Info about signatures; gives the *monomorphic*
+ -- Id for variables with a type signature
-> Name
- -> TcType s -- Expected type
- -> TcM s (TcIdBndr s) -- The monomorphic Id; this is put in the pattern itself
+
+ -> TcType -- Expected type, derived from the context
+ -- In the case of a function with a rank-2 signature,
+ -- this type might be a forall type.
+ -- INVARIANT: if it is, the foralls will always be visible,
+ -- not hidden inside a mutable type variable
+
+ -> TcM s TcId -- The monomorphic Id; this is put in the pattern itself
tcVarPat sig_fn binder_name pat_ty
= case sig_fn binder_name of
returnTc bndr_id
Just bndr_id -> tcAddSrcLoc (getSrcLoc binder_name) $
- unifyTauTy pat_ty (idType bndr_id) `thenTc_`
+ unifyTauTy (idType bndr_id) pat_ty `thenTc_`
returnTc bndr_id
\end{code}
%************************************************************************
\begin{code}
-tcPat :: (Name -> Maybe (TcIdBndr s)) -- Info about signatures
+tcPat :: (Name -> Maybe TcId) -- Info about signatures; gives the *monomorphic*
+ -- Id for variables with a type signature
-> 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
+ -> TcType -- Expected type; see invariant in tcVarPat
+ -> TcM s (TcPat,
+ LIE, -- Required by n+k and literal pats
+ 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.
- LIE s) -- Dicts or methods [see below] bound by the pattern
+ LIE) -- Dicts or methods [see below] bound by the pattern
+ -- from existential constructor patterns
\end{code}
\begin{code}
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)
+ returnTc (VarPat bndr_id, emptyLIE, emptyBag, unitBag (name, bndr_id), emptyLIE)
tcPat sig_fn (LazyPatIn pat) pat_ty
= tcPat sig_fn pat pat_ty `thenTc` \ (pat', lie_req, tvs, ids, lie_avail) ->
= 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) $
- returnTc (AsPat (TcId bndr_id) pat', lie_req,
- tvs, (name, bndr_id) `consBag` ids,
- lie_avail)
+ returnTc (AsPat bndr_id pat', lie_req,
+ tvs, (name, bndr_id) `consBag` ids, lie_avail)
tcPat sig_fn WildPatIn pat_ty
= returnTc (WildPat pat_ty, emptyLIE, emptyBag, emptyBag, emptyLIE)
tcPat sig_fn (ParPatIn parend_pat) pat_ty
= tcPat sig_fn parend_pat pat_ty
+
+tcPat sig_fn (SigPatIn pat sig) pat_ty
+ = tcHsType sig `thenTc` \ sig_ty ->
+
+ -- Check that the signature isn't a polymorphic one, which
+ -- we don't permit (at present, anyway)
+ checkTc (isTauTy sig_ty) (polyPatSig sig_ty) `thenTc_`
+
+ unifyTauTy pat_ty sig_ty `thenTc_`
+ tcPat sig_fn pat sig_ty
\end{code}
%************************************************************************
= ASSERT( null extras )
tc_fields field_tys rpats `thenTc` \ (rpats', lie_req1, tvs1, ids1, lie_avail1) ->
- tcLookupGlobalValue field_label `thenNF_Tc` \ sel_id ->
+ tcLookupValue 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',
\begin{code}
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) ->
+ tcLookupValueByKey eqClassOpKey `thenNF_Tc` \ sel_id ->
+ newMethod (PatOrigin pat) sel_id [stringTy] `thenNF_Tc` \ (lie, eq_id) ->
let
comp_op = HsApp (HsVar eq_id) (HsLitOut lit stringTy)
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 ->
+ tcLookupValueByKey geClassOpKey `thenNF_Tc` \ ge_sel_id ->
+ tcLookupValueByKey minusClassOpKey `thenNF_Tc` \ minus_sel_id ->
newOverloadedLit origin
(OverloadedIntegral i) pat_ty `thenNF_Tc` \ (over_lit_expr, lie1) ->
- 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) ->
+ newMethod origin ge_sel_id [pat_ty] `thenNF_Tc` \ (lie2, ge_id) ->
+ newMethod origin minus_sel_id [pat_ty] `thenNF_Tc` \ (lie3, minus_id) ->
- returnTc (NPlusKPat (TcId bndr_id) lit pat_ty
+ returnTc (NPlusKPat bndr_id lit pat_ty
(SectionR (HsVar ge_id) over_lit_expr)
(SectionR (HsVar minus_id) over_lit_expr),
lie1 `plusLIE` lie2 `plusLIE` lie3,
Helper functions
\begin{code}
-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 :: (Name -> Maybe TcId) -- Info about signatures
+ -> [RenamedPat] -> [TcType] -- Excess 'expected types' discarded
+ -> TcM s ([TcPat],
+ LIE, -- Required by n+k and literal pats
+ Bag TcTyVar,
+ Bag (Name, TcId), -- Ids bound by the pattern
+ LIE) -- Dicts bound by the pattern
tcPats sig_fn [] tys = returnTc ([], emptyLIE, emptyBag, emptyBag, emptyLIE)
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) ->
+ tcLookupValueByKey eqClassOpKey `thenNF_Tc` \ eq_sel_id ->
+ newMethod origin eq_sel_id [pat_ty] `thenNF_Tc` \ (lie2, eq_id) ->
returnTc (NPat lit pat_ty (HsApp (HsVar eq_id)
over_lit_expr),
\begin{code}
tcConstructor pat con_name pat_ty
= -- Check that it's a constructor
- tcLookupGlobalValue con_name `thenNF_Tc` \ con_id ->
+ tcLookupValue con_name `thenNF_Tc` \ con_id ->
case isDataConId_maybe con_id of {
Nothing -> failWithTc (badCon con_id);
Just data_con ->
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
+ ex_theta' = substTopTheta tenv ex_theta
+ arg_tys' = map (substTopTy tenv) arg_tys
n_ex_tvs = length ex_tvs
ex_tvs' = take n_ex_tvs all_tvs'
badFieldCon con field
= hsep [ptext SLIT("Constructor") <+> quotes (ppr con),
ptext SLIT("does not have field"), quotes (ppr field)]
+
+polyPatSig :: TcType -> SDoc
+polyPatSig sig_ty
+ = hang (ptext SLIT("Polymorphic type signature in pattern"))
+ 4 (ppr sig_ty)
\end{code}
projects / ghc-hetmet.git / blobdiff