// Wraps long lines in standard input.
// Demonstrates D's powerful array manipulation facility and generic
// algorithms.

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

void main() {
	int width = 80;

	foreach (line; stdin.byLine()) {
		while (line.length > width) {
			// Find longest space-terminated prefix of line that
			// fits in width, and wrap it there.
			char[] fits = find(retro(line[0..width]), " ").source;
			writeln(fits);
			line = line[fits.length .. $];
		}
		writeln(line);
	}
}

On Wednesday, 18 April 2012 at 01:59:19 UTC, H. S. Teoh wrote:
> // Wraps long lines in standard input.
> // Demonstrates D's powerful array manipulation facility and generic
> // algorithms.
>
> import std.algorithm;
> import std.array;
> import std.range;
> import std.stdio;
>
> void main() {
> 	int width = 80;
>
> 	foreach (line; stdin.byLine()) {
> 		while (line.length > width) {
> 			// Find longest space-terminated prefix of line that
> 			// fits in width, and wrap it there.
> 			char[] fits = find(retro(line[0..width]), " ").source;
> 			writeln(fits);
> 			line = line[fits.length .. $];
> 		}
> 		writeln(line);
> 	}
> }

There is a bug in this code. If a line is longer then width but doesn't contain spaces, find will return an empty range and the length of line will not decrease on each while loop iteration. So there is an endless loop.