Why doesn't join() call str() on its arguments?

[Terry Reedy]

"Nick Coghlan" <ncoghlan at iinet.net.au> wrote in message 
news:421477D4.2050305 at iinet.net.au...
> This seems to be the last relevant message in the thread:
> http://mail.python.org/pipermail/python-dev/2004-August/048516.html

> So it was tried, but we found too many weird corner cases we weren't 
> quite sure
> what to do with. At that point, "explicit is better than implicit" kicked 
> in :)
> A shame, since it was both faster and more convenient than using a list 
> comp. But the convenience wasn't worth the ambiguity of the semantics.

Your experience, where you made an honest go of implementation, and the 
error catching argument, convince me that explicit is better for this case.

I was thinking, 'Well, print autoconverts' (as documented).  But it 
requires that each item be listed.  And if there is any ambiguity, no harm 
since it is only meant for quick convenience anyway and not exact 
char-by-char control.  Join, on the other hand, often gets a pre-existing 
list.  If that is known (thought to be) all strings, then mapping str is a 
waste as well as an error mask.  In not, map(str,...) is only 9 extra 
chars.

Terry J. Reedy