TcRules: Typechecking transformation rules
\begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module TcRules ( tcRules ) where
#include "HsVersions.h"
import Name
import SrcLoc
import Outputable
+import FastString
\end{code}
\begin{code}
tcRules :: [LRuleDecl Name] -> TcM [LRuleDecl TcId]
-tcRules decls = mappM (wrapLocM tcRule) decls
+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) $
- traceTc (ptext SLIT("---- Rule ------")
- <+> ppr name) `thenM_`
- newFlexiTyVarTy openTypeKind `thenM` \ rule_ty ->
+ = addErrCtxt (ruleCtxt name) $ do
+ traceTc (ptext SLIT("---- Rule ------") <+> ppr name)
+ rule_ty <- newFlexiTyVarTy openTypeKind
-- Deal with the tyvars mentioned in signatures
- tcRuleBndrs vars (\ ids ->
+ (ids, lhs', rhs', lhs_lie, rhs_lie) <-
+ tcRuleBndrs vars $ \ ids -> do
-- Now LHS and RHS
- getLIE (tcMonoExpr lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
- getLIE (tcMonoExpr rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
- returnM (ids, lhs', rhs', lhs_lie, rhs_lie)
- ) `thenM` \ (ids, lhs', rhs', lhs_lie, rhs_lie) ->
+ (lhs', lhs_lie) <- getLIE (tcMonoExpr lhs rule_ty)
+ (rhs', rhs_lie) <- getLIE (tcMonoExpr rhs rule_ty)
+ return (ids, lhs', rhs', lhs_lie, rhs_lie)
-- Check that LHS has no overloading at all
- tcSimplifyRuleLhs lhs_lie `thenM` \ (lhs_dicts, lhs_binds) ->
+ (lhs_dicts, lhs_binds) <- tcSimplifyRuleLhs lhs_lie
-- Gather the template variables and tyvars
let
-- during zonking (see TcHsSyn.zonkRule)
--
forall_tvs = tyVarsOfTypes (rule_ty : map idType tpl_ids)
- in
+
-- RHS can be a bit more lenient. In particular,
-- we let constant dictionaries etc float outwards
--
-- NB: tcSimplifyInferCheck zonks the forall_tvs, and
-- knocks out any that are constrained by the environment
- getInstLoc (SigOrigin (RuleSkol name)) `thenM` \ loc ->
- tcSimplifyInferCheck loc
- forall_tvs
- lhs_dicts rhs_lie `thenM` \ (forall_tvs1, rhs_binds) ->
- zonkQuantifiedTyVars forall_tvs1 `thenM` \ forall_tvs2 ->
- -- This zonk is exactly the same as the one in TcBinds.generalise
-
- returnM (HsRule name act
- (map (RuleBndr . noLoc) (forall_tvs2 ++ tpl_ids)) -- yuk
+ 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)) -- yuk
(mkHsDictLet lhs_binds lhs') fv_lhs
(mkHsDictLet rhs_binds rhs') fv_rhs)