Re: Make foreach element optional
On Tuesday, 16 March 2021 at 16:29:45 UTC, Imperatorn wrote:
On Tuesday, 16 March 2021 at 13:52:29 UTC, Per Nordlöw wrote:
On Tuesday, 16 March 2021 at 13:31:34 UTC, Imperatorn wrote:
foreach(0..n) could work. Why though.
When performing a side-effect n times.
Then why not just do:
auto times(alias F, T)(T number)
{
return number.iota.each!(_ => F());
}
void f()
{
writeln("hi");
}
n.times!(f);
?
To my knowledge, there's nothing like this in the standard
library or the language. I used something similar but eventually
decided it was simpler to use the original foreach. It'd honestly
have to be a language change to be useful. (Given the benefit, I
doubt this would happen.)
Re: Make foreach element optional
On Tuesday, 16 March 2021 at 15:02:54 UTC, Steven Schveighoffer
wrote:
On 3/16/21 8:49 AM, Per Nordlöw wrote:
I find myself writing
foreach (_; 0 .. n)
doSomething(); // no using the variable `_`
.
What about relaxing the syntax to allow
foreach (; 0 .. n)
and/or
foreach (0 .. n)
?
Thereby making the `ForeachTypeList` of `AggregateForeach` in
the grammar rule [1] optional.
[1] https://dlang.org/spec/statement.html#foreach-statement
Meh, is this a common need though? The first form isn't
terrible.
In general, I'd say it would be nice to designate _ as an
unused variable (i.e. not allowed to access it, and it doesn't
trigger shadowing errors). It's like this in Swift for instance.
-Steve
the _ as unused variable would be useful when the parameter has
out parameter but wouldn't to ignore it. C# does something like
this currently.
int foo(int x, out bool state) { }
// only wants return value
int y = foo(x, _);
Re: Make foreach element optional
On Tuesday, 16 March 2021 at 13:52:29 UTC, Per Nordlöw wrote:
On Tuesday, 16 March 2021 at 13:31:34 UTC, Imperatorn wrote:
foreach(0..n) could work. Why though.
When performing a side-effect n times.
Then why not just do:
auto times(alias F, T)(T number)
{
return number.iota.each!(_ => F());
}
void f()
{
writeln("hi");
}
n.times!(f);
?
Re: Make foreach element optional
On Tuesday, 16 March 2021 at 12:49:13 UTC, Per Nordlöw wrote:
I find myself writing
foreach (_; 0 .. n)
doSomething(); // no using the variable `_`
.
What about relaxing the syntax to allow
foreach (; 0 .. n)
and/or
foreach (0 .. n)
?
Thereby making the `ForeachTypeList` of `AggregateForeach` in
the grammar rule [1] optional.
[1] https://dlang.org/spec/statement.html#foreach-statement
The gain to altering the foreach statement is minimal since _ is
a nice convention to use if you don't need the value of the
counter.
Something like this gives cleaner code:
replicate(100) {
// do stuff with side effects
}
I don't know if it would be an opportunity for a compiler
optimization (probably not).
Re: Make foreach element optional
On 3/16/21 8:49 AM, Per Nordlöw wrote: I find myself writing foreach (_; 0 .. n) doSomething(); // no using the variable `_` . What about relaxing the syntax to allow foreach (; 0 .. n) and/or foreach (0 .. n) ? Thereby making the `ForeachTypeList` of `AggregateForeach` in the grammar rule [1] optional. [1] https://dlang.org/spec/statement.html#foreach-statement Meh, is this a common need though? The first form isn't terrible. In general, I'd say it would be nice to designate _ as an unused variable (i.e. not allowed to access it, and it doesn't trigger shadowing errors). It's like this in Swift for instance. -Steve
Re: Make foreach element optional
On Tuesday, 16 March 2021 at 13:31:34 UTC, Imperatorn wrote: foreach(0..n) could work. Why though. When performing a side-effect n times.
Re: Make foreach element optional
On Tuesday, 16 March 2021 at 12:49:13 UTC, Per Nordlöw wrote: I find myself writing foreach (_; 0 .. n) doSomething(); // no using the variable `_` . What about relaxing the syntax to allow foreach (; 0 .. n) and/or foreach (0 .. n) ? Thereby making the `ForeachTypeList` of `AggregateForeach` in the grammar rule [1] optional. [1] https://dlang.org/spec/statement.html#foreach-statement foreach(0..n) could work. Why though.
Make foreach element optional
I find myself writing foreach (_; 0 .. n) doSomething(); // no using the variable `_` . What about relaxing the syntax to allow foreach (; 0 .. n) and/or foreach (0 .. n) ? Thereby making the `ForeachTypeList` of `AggregateForeach` in the grammar rule [1] optional. [1] https://dlang.org/spec/statement.html#foreach-statement
