Real time input

[haible (Bruno Haible)]

[Forwarded from Ed Loper <ed@syse>???.]

-------------------------------------------------------------------------------

I have a question about the listen and read-char-no-hang 
functions.  I'm trying to make a program which will read 
characters as they are typed, but do other things if they 
are not typed.  This is, as far as I can tell, the 
function of read-char-no-hang.  However, clisp seems to 
wait until a newline has been pressed before putting 
typed characters into the buffer; thus, if a user types
"h", my program won't see it until he types a newline, at
which point it will see an "#\h" and a "#\Newline".  clisp
also seems to echo each character to the screen when it is
typed; I would prefer if it would let me handle this.  Is
this all happening because of the read-eval-print loop?  Is
there a special variable which I need to set in order to
tell clisp that I want each character put into the input
buffer as it is read?  Or is there some other way in which
I should arrange for characters to be read as soon as they
are typed?  I've looked through a lot of common lisp docs
and books with no success, so I thought that it might be
something particular to clisp.

In case it matters, I am running:
 - A version of clisp that was copyrighted 1994 (I can't 
   figure out where the version number
   is) on version 

The operating system is:
 - Version 1.1.73 of Linux (Slackware version 2.0)

A short function which demonstrates this problem is:
;;
;; This function creates a busy loop which echos characters
;; whenever it recieves them.  When it recieves the character
;; #\q, it immediately exits.
;;
(defun read-characters ()                                            
  (let ((input nil))                        ;Bind a var for input
    (loop                                   ;Loop until #\q is hit
     (when (setf input (read-char-no-hang)) ;When a char is typed,
         (write input)                      ;  write that character
         (format t "~%"))                   ;Write a newline
     (when (equal input #\q)                ;When the char is q,
           (return t)))))                   ;  exit and return t

I also had four less important questions:
  1. How portable is the screen package?  Is it only portable across
     common lisp, or is it a defined standard, a de facto standard,
     or is it only implemented in clisp?

  2. Because clisp doesn't compile to a machine-specific binary, is
     there no way to make a stand alone executable?  Is there some
     way to link clisp and my program into one binary file, and if
     so, do I have to worry about licensing stuff etc?  

  3. What x-windows packages are available for clisp? (clx, garnet, 
     etc.) and where can I get them?

  4. Eric Sauthier wrote that "One way to overcome this 'slowness'
     would be to add a step to the compiler, specific to a particular
     architexture, which would translate the intermediate language
     representation into machine instructions."  I was wondering if
     anyone was working on such an entity for linux.  I am neither
     a linux guru nor a lisp guru, so I couldn't give much help, but
     I would be interrested in such a project's progress.  I was also
     wondering whether it would in fact be easier to compile from
     clisp binaries to linux binaries, or whether it would be easier
     to compile directly from common lisp: are the binaries simpler
     then the common lisp code?  Do they only use a few commands?  If
     so, are they commands like first, rest, and list, or commands
     like jump, copy-memory, and add?

Thanx in advance for any help you can give me...

                                Edward Loper