From: Yukihiro Matsumoto Date: 2007-09-27T12:35:25+09:00 Subject: Re: Array#-, &, |, uniq don't use == Hi, In message "Re: Array#-, &, |, uniq don't use ==" on Thu, 27 Sep 2007 08:22:48 +0900, murphy writes: |Is this a feature? Why do some methods use "=="-equality and others |"eql?"-equality? It's a feature, to reduce complexity order from O(m^n) to O(mn). matz.