From: sof <unknown>
Date: Thu, 21 Jan 1999 15:08:51 +0000 (+0000)
Subject: [project @ 1999-01-21 15:08:51 by sof]
X-Git-Tag: Approx_2487_patches~31
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=40317587d007023ec09db8ecab3e1a11f8670649;p=ghc-hetmet.git

[project @ 1999-01-21 15:08:51 by sof]
With Haskell98, Enum.enumFromThen can generate sequences that
are either increasing, decreasing or infinite.
---

diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index cc3e205..cab4e7c 100644
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -505,7 +505,12 @@ gen_Enum_binds tycon
 	    HsPar (enum_from_then_to_Expr
 		    (mk_easy_App mkInt_RDR [ah_RDR])
 		    (mk_easy_App mkInt_RDR [bh_RDR])
-		    (HsVar (maxtag_RDR tycon)))
+		    (HsIf  (HsApp (HsApp (HsVar gt_RDR)
+					 (HsVar a_RDR))
+					 (HsVar b_RDR))
+			   (HsLit (HsInt 0))
+			   (HsVar (maxtag_RDR tycon))
+			   tycon_loc))
 
     from_enum
       = mk_easy_FunMonoBind tycon_loc fromEnum_RDR [a_Pat] [] $