%
% (c) The University of Glasgow 2006
% (c) The AQUA Project, Glasgow University, 19931998
%
TcRules: Typechecking transformation rules
\begin{code}
module TcRules ( tcRules ) where
import HsSyn
import TcRnMonad
import TcSimplify
import TcMType
import TcType
import TcHsType
import TcExpr
import TcEnv
import Inst
import Id
import Name
import SrcLoc
import Outputable
import FastString
\end{code}
\begin{code}
tcRules :: [LRuleDecl Name] -> TcM [LRuleDecl TcId]
tcRules decls = mapM (wrapLocM tcRule) decls
tcRule :: RuleDecl Name -> TcM (RuleDecl TcId)
tcRule (HsRule name act vars lhs fv_lhs rhs fv_rhs)
= addErrCtxt (ruleCtxt name) $ do
traceTc (ptext (sLit "---- Rule ------") <+> ppr name)
rule_ty <- newFlexiTyVarTy openTypeKind
(ids, lhs', rhs', lhs_lie, rhs_lie) <-
tcRuleBndrs vars $ \ ids -> do
(lhs', lhs_lie) <- getLIE (tcMonoExpr lhs rule_ty)
(rhs', rhs_lie) <- getLIE (tcMonoExpr rhs rule_ty)
return (ids, lhs', rhs', lhs_lie, rhs_lie)
(lhs_dicts, lhs_binds) <- tcSimplifyRuleLhs lhs_lie
let
tpl_ids = map instToId lhs_dicts ++ ids
forall_tvs = tyVarsOfTypes (rule_ty : map idType tpl_ids)
loc <- getInstLoc (SigOrigin (RuleSkol name))
(forall_tvs1, rhs_binds) <- tcSimplifyInferCheck loc
forall_tvs
lhs_dicts rhs_lie
return (HsRule name act
(map (RuleBndr . noLoc) (forall_tvs1 ++ tpl_ids))
(mkHsDictLet lhs_binds lhs') fv_lhs
(mkHsDictLet rhs_binds rhs') fv_rhs)
tcRuleBndrs :: [RuleBndr Name] -> ([Id] -> TcM a) -> TcM a
tcRuleBndrs [] thing_inside = thing_inside []
tcRuleBndrs (RuleBndr var : vars) thing_inside
= do { ty <- newFlexiTyVarTy openTypeKind
; let id = mkLocalId (unLoc var) ty
; tcExtendIdEnv [id] $
tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }
tcRuleBndrs (RuleBndrSig var rn_ty : vars) thing_inside
= do { let ctxt = FunSigCtxt (unLoc var)
; (tyvars, ty) <- tcHsPatSigType ctxt rn_ty
; let skol_tvs = tcSkolSigTyVars (SigSkol ctxt) tyvars
id_ty = substTyWith tyvars (mkTyVarTys skol_tvs) ty
id = mkLocalId (unLoc var) id_ty
; tcExtendTyVarEnv skol_tvs $
tcExtendIdEnv [id] $
tcRuleBndrs vars (\ids -> thing_inside (id:ids)) }
ruleCtxt :: FastString -> SDoc
ruleCtxt name = ptext (sLit "When checking the transformation rule") <+>
doubleQuotes (ftext name)
\end{code}