Defining a static array with values in a range

[bearophile via Digitalmars-d-learn]

tcak:
> Well, that's just disguising what we can't do.

When the a..b syntax was added to foreach() someone criticized 
that syntax saing it's a "one trick pony", and indeed I don't 
know why Walter didn't make it a little more first-class.

But note that in D the a..b ranges are always open on the right, 
so 'a'..'z' can't include the 'z'.

What do you think of this?


import std.stdio, std.range, std.algorithm, std.array;

auto charInterval(in char a, in char b) pure nothrow @safe @nogc {
     return iota(a, b + 1).map!(i => cast(char)i);
}

void main() @safe {
     char[] arr = chain(charInterval('a', 'z'),
                        charInterval('A', 'Z'),
                        charInterval('0', '9')).array;
     arr.writeln;
}


charInterval can of course become eager too, so you just need ~ 
to concatenate the results:


import std.stdio, std.range, std.algorithm, std.array;

char[] charInterval(in char a, in char b) pure nothrow @safe {
     return iota(a, b + 1).map!(i => cast(char)i).array;
}

void main() @safe {
     char[] arr = charInterval('a', 'z') ~
                  charInterval('A', 'Z') ~
                  charInterval('0', '9');
     arr.writeln;
}


Bye,
bearophile