I find this idea very intriguing. ,= looks so perfect for arrays that it seems almost essential. That is to say, it is as if such a combination of two characters exists merely to fit this use. It feels so right
, so devilishly Perlish.
However, issues arise. Firstly, as brought up above, it could be confused for .=, as I personally confused myself reading the post. Secondly, it is a bit much, a bit excessive even for Perl, to add an operator to do exactly what a function already does. Most crucially, and thirdly, Perl's operators are scalar operators. Perl is a scalar-based language. Deviation from that should be done only as an act of revolutionary policy, not as a whim for a delightful yet unnecessary feature.