Paul Moore wrote:
Where in [fn(x) for x in lst if cond] is the * allowed? fn(*x)? *fn(x)?
Obviously you're *allowed* to put fn(*x), because that's already a valid function call, but the only *new* place we're talking about, and proposing new semantics for, is in front of the expression representing items to be added to the list, i.e. [*fn(x) for ...]
I think it's probably time for someone to describe the precise syntax (as BNF, like the syntax in the Python docs at https://docs.python.org/3.6/reference/expressions.html#displays-for-lists-sets-and-dictionaries
Replace comprehension ::= expression comp_for with comprehension ::= (expression | "*" expression) comp_for
and semantics (as an explanation of how to rewrite any syntactically valid display as a loop).
The expansion of the "*" case is the same as currently except that 'append' is replaced by 'extend' in a list comprehension, 'yield' is replaced by 'yield from' in a generator comprehension. If we decided to also allow ** in dict comprehensions, then the expansion would use 'update'. -- Greg _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
