I was curious how and why return annotations use the arrow `->` symbol, so I went spelunking into the depths of the Python-Ideas and Python-Dev mailing lists.
Much to my surprise, I couldn't find any discussion or debate about it. Eventually I tracked the discussion back to a mailing list I didn't even know existed, Types-Sig, all the way back to 13th Dec 1999, where I found this email by Tim Hochberg: https://mail.python.org/pipermail/types-sig/1999-December/000281.html suggesting the arrow symbol for all type declarations. This appears to be the first suggestion of the arrow symbol for type annotations in Python. I am surprised that type checking was being discussed so long ago. Python was not even a decade old, and if my calculations are correct, the versions at the time would have been 1.5.2 and 1.6.0. But I am especially amazed that the choice of symbol seems to have been accepted with very little argument or debate about alternative colours for the bike-shed. I can't find any suggestions for alternative symbols such as `=>` `-->` `==>` `->>` etc, and very little for keywords such as `as`. The day after Tim posted, Tony Lownds suggested `as` and then immediately suggested using Tim's arrow symbol for the return type only: https://mail.python.org/pipermail/types-sig/1999-December/000335.html and then as far as I can tell, we've never looked back. If there is anyone whose memory reaches back that far, does that sound right? -- Steve _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/4ZZP5DJARHHKN4HBC4JHHRIV5Z2EZOVT/ Code of Conduct: http://python.org/psf/codeofconduct/
