X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FcoreSyn%2FCoreSyn.lhs;h=4ec954ce6a5b6282abc0438cb7ecb5aeecc3050b;hb=618380a7fa2ca7b75b2b6a5bfa7eac4a86941510;hp=09e41aaeb959131750a393e0054dea6072c23bda;hpb=479f4cac9815c88e91492913a1247d8c6f53b659;p=ghc-hetmet.git

diff --git a/compiler/coreSyn/CoreSyn.lhs b/compiler/coreSyn/CoreSyn.lhs
index 09e41aa..4ec954c 100644
--- a/compiler/coreSyn/CoreSyn.lhs
+++ b/compiler/coreSyn/CoreSyn.lhs
@@ -218,14 +218,23 @@ data CoreRule
 	-- Locality
 	ru_local :: Bool	-- The fn at the head of the rule is
 				-- defined in the same module as the rule
+				-- and is not an implicit Id (like a record sel
+				-- class op, or data con)
+		-- NB: ru_local is *not* used to decide orphan-hood
+		--	c.g. MkIface.coreRuleToIfaceRule
     }
 
   | BuiltinRule {		-- Built-in rules are used for constant folding
 	ru_name :: RuleName,	-- and suchlike.  It has no free variables.
 	ru_fn :: Name,		-- Name of the Id at 
 				-- the head of this rule
-	ru_nargs :: Int,	-- Number of args that ru_try expects
+	ru_nargs :: Int,	-- Number of args that ru_try expects,
+				-- including type args
 	ru_try  :: [CoreExpr] -> Maybe CoreExpr }
+		-- This function does the rewrite.  It given too many
+		-- arguments, it simply discards them; the returned CoreExpr
+		-- is just the rewrite of ru_fn applied to the first ru_nargs args
+		-- See Note [Extra args in rule matching] in Rules.lhs
 
 isBuiltinRule (BuiltinRule {}) = True
 isBuiltinRule _		       = False