Add comment for the invariant that DataAlt is never a newtype

133d0902 · simonpj@microsoft.com · 6f873493 · 133d0902
Commit 133d0902 authored Sep 06, 2006 by simonpj@microsoft.com
Hide whitespace changes
Inline Side-by-side

Showing with 2 additions and 1 deletion

compiler/coreSyn/CoreSyn.lhs compiler/coreSyn/CoreSyn.lhs +2 -1

No files found.
--- 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)