From d07fc9735f40e545edda456e15dbab783c500f6a Mon Sep 17 00:00:00 2001
From: Gabriel Dos Reis <gdr@axiomatics.org>
Date: Sun, 17 Jan 2016 22:53:01 -0800
Subject: subtractIfCan$CancellationAbelianMonoid: return the more principled
 Maybe %

---
 src/algebra/integer.spad.pamphlet | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/algebra/integer.spad.pamphlet')

diff --git a/src/algebra/integer.spad.pamphlet b/src/algebra/integer.spad.pamphlet
index a91b6d63..fde8ef88 100644
--- a/src/algebra/integer.spad.pamphlet
+++ b/src/algebra/integer.spad.pamphlet
@@ -251,8 +251,8 @@ NonNegativeInteger: Join(OrderedAbelianMonoidSup,Monoid) with
       shift(x:%, n:Integer):% == ASH(x,n)$Lisp
       subtractIfCan(x, y) ==
         c:Integer := rep x - rep y
-        negative? c => "failed"
-        per c
+        negative? c => nothing
+        just per c
 
 @
 
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