non-blocking keyboard input inside customized repl

non-blocking keyboard input inside customized repl

[Peter Santoro]

I would like to be able use non-blocking keyboard input in my customized 
REPL user interface.  Is there a non-blocking read-char available in 
guile, so that the ENTER key doesn't always have to be pressed?

Thanks for your help,


Peter



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Re: non-blocking keyboard input inside customized repl

[Paul Jarc]

Peter Santoro <peter@pscomp.com> wrote:
> I would like to be able use non-blocking keyboard input in my
> customized REPL user interface.  Is there a non-blocking read-char
> available in guile, so that the ENTER key doesn't always have to be
> pressed?

It sounds like what you want is raw terminal input.  Non-blocking
input is different: it means that (read-char) will return immediately
(possibly throwing an exception) even if there is nothing to read yet.

For raw terminal input, you'd need tcsetattr, which doesn't seem to be
directly available in Guile.  But maybe you can use the readline
module to do what you want.


paul


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Re: non-blocking keyboard input inside customized repl

[Peter Santoro]

Paul Jarc wrote:

>Peter Santoro <peter@pscomp.com> wrote:
>  
>
>>I would like to be able use non-blocking keyboard input in my
>>customized REPL user interface.  Is there a non-blocking read-char
>>available in guile, so that the ENTER key doesn't always have to be
>>pressed?
>>    
>>
>
>It sounds like what you want is raw terminal input.  Non-blocking
>input is different: it means that (read-char) will return immediately
>(possibly throwing an exception) even if there is nothing to read yet.
>
>For raw terminal input, you'd need tcsetattr, which doesn't seem to be
>directly available in Guile.  But maybe you can use the readline
>module to do what you want.
>
>
>paul
>
>  
>
Paul, you are correct.  I did mean to use "raw terminal" input instead 
of "non-blocking" input.  I actually got this working in mzscheme and 
will endeavor to port over to guile.

Thanks,

Peter



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Re: non-blocking keyboard input inside customized repl

[Peter Santoro]

Paul Jarc wrote:

>Peter Santoro <peter@pscomp.com> wrote:
>  
>
>>I would like to be able use non-blocking keyboard input in my
>>customized REPL user interface.  Is there a non-blocking read-char
>>available in guile, so that the ENTER key doesn't always have to be
>>pressed?
>>    
>>
>
>It sounds like what you want is raw terminal input.  Non-blocking
>input is different: it means that (read-char) will return immediately
>(possibly throwing an exception) even if there is nothing to read yet.
>
>For raw terminal input, you'd need tcsetattr, which doesn't seem to be
>directly available in Guile.  But maybe you can use the readline
>module to do what you want.
>
>
>paul
>
>  
>
Thanks for the suggestions.  I tried the following in guile 1.6.1 and it works ok.  As I'm not a
 scheme guru, any suggestions for improvement are welcomed.


Peter


(define (term:reset settings)
  (system (string-append "stty " settings)))

(define (term:get-tty-settings)
  (shell-command-to-string "stty -g"))

(define (term:set-raw)
  (system "stty -icanon -echo min 1 time 0"))

(define (read-char-immediate)
  (if (not (isatty? (current-output-port))) (error "Not running with a tty."))
  (let ((tty-settings (term:get-tty-settings)))
    (term:set-raw)
    (let ((ch (read-char)))
      (term:reset tty-settings)
        ch )))

(define (with-immediate-read-char thunk)
  (if (not (isatty? (current-output-port))) (error "Not running with a tty."))
  (let ((tty-settings (term:get-tty-settings)))
    (term:set-raw)
    (let ((res (thunk)))
      (term:reset tty-settings)
      res )))




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