On Tue, Mar 5, 2019 at 6:07 PM Raymond Hettinger < firstname.lastname@example.org> wrote:
On Mar 5, 2019, at 2:13 PM, Greg Ewing email@example.com
Rhodri James wrote:
I have to go and look in the documentation because I expect the union
operator to be '+'.
Anyone raised on Pascal is likely to find + and * more natural. Pascal doesn't have bitwise operators, so it re-uses + and * for set operations. I like the economy of this arrangement -- it's not as if there's any other obvious meaning that + and * could have for sets.
The language SETL (the language of sets) also uses + and * for set operations.¹
So the secret is out: Python inherits a lot from SETL, through ABC -- ABC was heavily influenced by SETL.
¹ https://www.linuxjournal.com/article/6805 ² https://www.python.org/dev/peps/pep-0218/