hello

#!ff needs
\ $Id: hello,v 1.1 2006/05/08 19:55:06 lavarenn Exp $
\ Any text after backslash+space is a comment to end-of-line.
\ This file is executable by the shell (/bin/sh or other)
\ thanks to its first two characters (#!) which trigger the
\ shell to execute the command "ff needs ./thisfilename"
\ (where thisfilename is a placeholder for this file's name).
\ This triggers ff to load (at tib) and evaluate the string
\ "needs ./thisfilename", then needs loads (after the string)
\ thisfilename contents, skips its first line if beginning with #!,
\ then evaluates the rest: if this ever returns, then ff enters
\ the user interaction loop (repeat prompt read compiler again).

."hello_world!" bye

As "bye" returns from ff to the shell, the remaining
of this file contents after "bye" is ignored by ff.