$ perldoc perlhist ... Perl 1 introduced Perl to the world, and changed /\(...\|...\)/ to /(...|...)/. \(Dan Faigin still hasn't forgiven me. :−\)
となっていて、Perl version 0の頃はsed形式だったんだなと。
変えた理由は想像がつくけど、一応調べてみると
It turns out that you use the metacharacters much more frequently than you do the literal characters, so it made sense to change Perl so that /(.*)/ defined a substring that could be referenced later, while /\(.*\)/ matched a sequence inside literal parentheses.
その通りだなあ。
ちなみにDan FaiginがLarry Wallを許さないのは、Danのスクリプトをこの変更で全部ダメにしてしまったからとのこと
This change broke all of Dan Faigin’s scripts. I think he’s forgiven me by now, even if he won’t admit it.