Scheme - Updating and displaying values in-place on a screen

Author

Updating and displaying values in-place on a screen

Förster vom Silberwald

2006-09-05, 8:01 am

Hello: Is that possible: I want a counter, lets say from 1 to 100,
which appears on the screen and counts and being displayed "in-place".

I tried print, write, display, but with no avail because the result
looks as follows, either: 1 2 3 4 5 etc. or

1
2
3
4
etc.

But I want the counter similar to a digital clock so to speak.

Thanks,
Schneewittchen

Jens Axel Søgaard

2006-09-05, 8:01 am

Förster vom Silberwald skrev:
> Hello: Is that possible: I want a counter, lets say from 1 to 100,
> which appears on the screen and counts and being displayed "in-place".
>
> I tried print, write, display, but with no avail because the result
> looks as follows, either: 1 2 3 4 5 etc. or
>
> 1
> 2
> 3
> 4
> etc.
>
> But I want the counter similar to a digital clock so to speak.

I believe the answer depends on the terminal.

The general idea is to

1. print the number
2. print a carriage return
3. go to 1.

However, if the terminal handles carriage return as a linefeed,
you need to print backspaces instead (or perhaps ^W).

--
Jens Axel Søgaard

int2k@gmx.net

2006-09-05, 7:02 pm

"F=F6rster vom Silberwald" <chain_lube@hotmail.com> writes:

> Hello: Is that possible: I want a counter, lets say from 1 to 100,
> which appears on the screen and counts and being displayed "in-place".
>
> I tried print, write, display, but with no avail because the result
> looks as follows, either: 1 2 3 4 5 etc. or
>
> 1
> 2
> 3
> 4
> etc.
>
> But I want the counter similar to a digital clock so to speak.

Jens is right. You just have to figure out the right escape sequences
for your terminal. I found a snippet of Python code which should help
with that [1]. Based on that, I wrote a toy Lisp program and it
worked in my XTerm. BTW, thanks for asking this question: I've been
wanting to do this myself for a couple of days now but I gave up the
first time I tried :-)

Greetings
Wolfram

Footnotes:=20
[1] <http://www.demonseed.net/~jp/code/ansi.py>

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