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--* Subject: extend fails on SingleInteger [extend.as][31.4 (current)]

--@ Fixed  by:  PI   Sun Mar 20 22:08:07 EST 1994 
--@ Tested by:  none 
--@ Summary:    no more a bug 


#include "aslib.as"

IntegralDomain : Category == Ring with
   unit? : % -> Boolean
   exquo : (%,%) -> Partial %


extend SingleInteger:Join(IntegralDomain,Logic,OrderedFinite,IntegerNumberSystem) ==
  SingleInteger add
     unit?(s:%):Boolean == s=1 or s=-1
     exquo(a:%, b:%):Partial(%) ==
         a rem b = 0 => [a quo b]
         failed