Georg Brandl wrote:
Lie Ryan schrieb:
Terry Reedy wrote:
Steven D'Aprano wrote:
On Sat, 20 Jun 2009 08:31:26 am Lie Ryan wrote: You don't like lambda? Fine, define an external function first. Then you can write:
filter(pred, (f(x) for x in seq))
There's no violation of DRY, there's no redundancy, there's no lambda, there's no "y" variable needed. What's ugly about it? I think its great and that it kills any justification for the proposal.
tjr I hate it. It mixes map/filter style and comprehension style; and the fact it does so in a single line only makes it worse. Not that it would be any better in two lines.
Taking this further, using only map/filter style like this
filter(pred, map(f, seq))
takes two steps. Why is it so bad that doing it in a listcomp
(el for el in (f(y) for y in seq) if el > 2)
takes two steps as well?
Georg
Comprehension, by its nature, is map+filter in a single expression. Nested comprehension is (map+filter)+(map+filter). (where + is some sort of function composition) The proposal enables comprehension to become filter+map+filter, map+filter, filter+map, or map-only; eliminating the redundant map in (map+filter)+(map+filter). The filter() and map() functions are two separate function in the first place, so there is no redundancy in it. Mixing the two styles is ugly since it means you have to think in two separate (though related) paradigms.