id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
694,lawbreaker in HughesPJ,maeder@…,,"the law ""empty is an identity for <> and $$"" is currently broken by
ie. isEmpty (empty<>empty) as Conal Elliot noted.

Either the test isEmpty or the combinators <>, <+>, $$, $+$ need to be fixed. My suggested patch for the for 4 combinators caused an object code explosion (see ticket #490). I've also sent a simple patch for isEmpty that seems to be less optimal (as the reduction of a document may occur twice).

I could supply another patch of the 4 combinators where only the base cases are swapped. 
This patch does not cause the explosion because the reordered base cases better fit to the left-associativity of the combinators. However, associativity does not help if one uses unfornate parentheses.

Anyway, HughesPJ should be fixed somehow
Cheers Christian",bug,closed,normal,6.4.2,libraries/base,6.4.1,fixed,,,Unknown/Multiple,Unknown/Multiple,,Easy (less than 1 hour),,,,