praise: optional comma at the end of argument list is a life saver for generated code

[Ali Çehreli]

Yes, accepting that trailing comma is very useful in many contexts.

Related, I use std.format's %( and %) specifiers, which automatically 
remove the extra delimiters at the end:

import std.stdio;

void main() {
   writefln!"%(%s, %)"([1, 2, 3]);
}

Prints

1, 2, 3

When we want, we can use %| to mean "keep the delimiters up to this place":

   writefln!"%(%s,%| %)"([1, 2, 3]);

Now the comma is printed as well but not the following space:

1, 2, 3,

I wish it had an additional feature where we could say "use this 
delimiter before the last one" so we could inject e.g. and "and":

1, 2, and 3

As far as I know, it doesn't exist.

Ali