import TcSimplify ( tcSimplifyToDicts, tcSimplifyInferCheck )
import TcMType ( newTyVarTy )
import TcType ( tyVarsOfTypes, openTypeKind )
-import TcIfaceSig ( tcCoreExpr, tcCoreLamBndrs, tcVar )
+import TcIfaceSig ( tcCoreExpr, tcCoreLamBndrs )
import TcMonoType ( tcHsSigType, UserTypeCtxt(..), tcAddScopedTyVars )
-import TcExpr ( tcMonoExpr )
-import TcEnv ( tcExtendLocalValEnv )
+import TcExpr ( tcCheckRho )
+import TcEnv ( tcExtendLocalValEnv, tcLookupGlobalId, tcLookupId )
import Inst ( instToId )
import Id ( idType, mkLocalId )
import Outputable
tcRule (IfaceRule name act vars fun args rhs src_loc)
= addSrcLoc src_loc $
addErrCtxt (ruleCtxt name) $
- tcVar fun `thenM` \ fun' ->
+ tcLookupGlobalId fun `thenM` \ fun' ->
tcCoreLamBndrs vars $ \ vars' ->
mappM tcCoreExpr args `thenM` \ args' ->
tcCoreExpr rhs `thenM` \ rhs' ->
returnM (IfaceRuleOut fun' (Rule name act vars' args' rhs'))
-tcRule (IfaceRuleOut fun rule) -- Built-in rules come this way
- = tcVar fun `thenM` \ fun' ->
+tcRule (IfaceRuleOut fun rule) -- Built-in rules, and only built-in rules,
+ -- come this way. Usually IfaceRuleOut is only
+ -- used for the *output* of the type checker
+ = tcLookupId fun `thenM` \ fun' ->
+ -- NB: tcLookupId, not tcLookupGlobalId
+ -- Reason: when compiling GHC.Base, where eqString is defined,
+ -- we'll get the builtin rule for eqString, but eqString
+ -- will be in the *local* type environment.
+ -- Seems like a bit of a hack
returnM (IfaceRuleOut fun' rule)
tcRule (HsRule name act vars lhs rhs src_loc)
tcExtendLocalValEnv ids $
-- Now LHS and RHS
- getLIE (tcMonoExpr lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
- getLIE (tcMonoExpr rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
+ getLIE (tcCheckRho lhs rule_ty) `thenM` \ (lhs', lhs_lie) ->
+ getLIE (tcCheckRho rhs rule_ty) `thenM` \ (rhs', rhs_lie) ->
returnM (ids, lhs', rhs', lhs_lie, rhs_lie)
) `thenM` \ (ids, lhs', rhs', lhs_lie, rhs_lie) ->
-- RULE: forall v. fst (ss v) = fst v
-- The type of the rhs of the rule is just a, but v::(a,(b,c))
--
- -- It's still conceivable that there may be type variables mentioned
- -- in the LHS, but not in the type of the lhs, nor in the binders.
- -- They'll get zapped to (), but that's over-constraining really.
- -- Let's see if we get a problem.
+ -- We also need to get the free tyvars of the LHS; but we do that
+ -- 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
tcSimplifyInferCheck (text "tcRule")
forall_tvs
lhs_dicts rhs_lie `thenM` \ (forall_tvs1, rhs_binds) ->