From 133d09024cdead191873088b7248f5d96aafe60f Mon Sep 17 00:00:00 2001
From: "simonpj@microsoft.com" <unknown>
Date: Wed, 6 Sep 2006 11:41:55 +0000
Subject: [PATCH] Add comment for the invariant that DataAlt is never a
 newtype

---
 compiler/coreSyn/CoreSyn.lhs |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/coreSyn/CoreSyn.lhs b/compiler/coreSyn/CoreSyn.lhs
index f83845f..a108945 100644
--- a/compiler/coreSyn/CoreSyn.lhs
+++ b/compiler/coreSyn/CoreSyn.lhs
@@ -112,7 +112,8 @@ type Arg b = Expr b		-- Can be a Type
 
 type Alt b = (AltCon, [b], Expr b)	-- (DEFAULT, [], rhs) is the default alternative
 
-data AltCon = DataAlt DataCon
+data AltCon = DataAlt DataCon	-- Invariant: the DataCon is always from 
+				-- a *data* type, and never from a *newtype*
 	    | LitAlt  Literal
 	    | DEFAULT
 	 deriving (Eq, Ord)
-- 
1.7.10.4