On 02/09/2011 04:08 AM, Nick Sabalausky wrote:
AUIU, foreach has both of these forms:
foreach(x; 0..5)
foreach(x; someRange)
Also, we have:
auto someRange = iota(0, 5);
Little idea: How about this genralized lowering?
0..5
// iota says "Gimme some sugar, baby."
// and thus it is lowered to ->
iota(0, 5)
Of course, if that hinders optimization for foreach(x; 0..5), then the
compiler could just "optimize" that particular case by not bothering with
the lowering and doing as it currently does.
But the benefit is things like this:
// Stealing Andrei's "filter even" example:
filter!`a % 2 == 0`(iota(1, 5))
// Give iota some sugar, baby:
filter!`a % 2 == 0`(1..5)
I suppose the obnoxious float-literal definition could get in the way, but
when is it ever legal syntax in D to have two numeric literals next to each
other? (And foreach seems ok with it anyway)
Pardon if this has already been suggested.
I like this. Maybe a slightly different approach would be for both 1..5 and
iota(1,5) to be expressions for a simple and range-semantic-compatible
struct-like thingy. Then, actually, iota would be superfluous, but some may
still like it syntactically or semantically (because Iota is explicitely
defined as a range type).
Side-question: what is actually 1..5 as of now for a thing? Or is it
conceptually "unconstructed" by rewriting to (probably) an ordinary for loop?
Anyway, the point above applies to language-side semantics, whatever
optimisation may happen.
Denis
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