On Thu, Oct 13, 2016, at 14:50, David Mertz wrote: > Neither of those follows conventional Python semantics for function > calling > or sequence unpacking. So maybe that remains a type error or syntax > error. But then we exclude a very common pattern of using comprehensions > to create collections of *transformed* data, not simply of filtered data.
[*map(math.exp, t) for t in [(1, 2), (3, 4)]] [*(math.exp(x) for x in t) for t in [(1, 2), (3, 4)]] I think "excluding" is a bit of a strong word - just because something doesn't address a mostly unrelated need doesn't mean it doesn't have any merit in its own right. Not every proposal is going to do everything. I think the key is that the person originally asking this thought of *x as a generalized "yield from x"-ish thing, for example: "a, *b, c" becomes "def f(): yield a; yield from b; yield c;" [a, *b, c] == list(f()) (a, *b, c) == tuple(f()) so, under a similar 'transformation', "*foo for foo in bar" likewise becomes "def f(): for foo in bar: yield from foo" bar = [(1, 2), (3, 4)] (*(1, 2), *(3, 4)) == == tuple(f()) [*(1, 2), *(3, 4)] == == list(f()) > In contrast, either of these are unambiguous and obvious: > > [math.exp(t) for t in flatten([(1,2),(3,4)])] > > Or: > > [math.exp(n) for t in [(1,2),(3,4)] for n in t] > > Obviously, picking math.exp() is arbitrary and any unary function would > be > the same issue. > > > -- > Keeping medicines from the bloodstreams of the sick; food > from the bellies of the hungry; books from the hands of the > uneducated; technology from the underdeveloped; and putting > advocates of freedom in prisons. Intellectual property is > to the 21st century what the slave trade was to the 16th. > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
