Fastest approach to returning a vector of elements choose 2

[adienes]

@narnold0

but how can one do such a thing in a single line if statement without calling something twice? Sorry if thats a dumb question lol

it is a good question, and one that has been discussed in the past

Proposal to extend the syntax of list comprehensions with a `let` clause

I would like to propose a new syntactic sugar to the list comprehension syntax. Take the following, somewhat forced example: [2abs(x) for x in -20:20 if abs(x) > 10] Here, the abs function is invoked twice. Of course, in this case, it is not a big deal, but it could be a more costly computation, or just a longer expression, which I don’t want to invoke or write down twice. So I can apply the following trick: [2abs_x for x in -20:20 for abs_x in [abs(x)] if abs_x > 10] Which works fine,…

I don’t think such a feature was ever ruled out, but it has also not yet been implemented

If you have this need, it may be difficult to do it as a snazzy comprehension one-liner.

You may notice that (i for i in 1:10 if iseven(i)) internally uses Iterators.Filter, but you are free to call Iterators.Filter directly

• (foo(x) for x in itr if cond(foo(x)))

becomes

• Iterators.Filter(cond, (foo(x) for x in itr))