> On Mar 5, 2019, at 2:13 PM, Greg Ewing <greg.ewing@canterbury.ac.nz> wrote:
>
> 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/