about Ball and Paddle game

wxie

Hi,

Recently I found this free game from
https://savannah.gnu.org/projects/ballandpaddle/

I am trying to make it work for Guile 3. However, there is one problem when running the game:
(list-set! ((0 0 32 12 100 0 0)) 0 (0 0 32 12 100 0 0))
In procedure set-car!: Wrong type argument in position 1 (expecting mutable pair): ((0 0 32 12 100 0 0))

It is from the file: ballandpaddle-extensions.scm:
(define set-bonus-timer-source #f)
(define (set-bonus-timer-source-aux game state)
(lambda (x y w h)
(let ((data (data state)))
(let ((bonus-timer-spec (game-instance:bonus-timer-spec data)))
(let ((source (list-ref bonus-timer-spec 1)))
(let ((frames (list-ref source 1)))
(list-set! frames 0 (list x y w h 100 0 0))))))))

I am not sure how to fix it. Is there anyone interested in trying this game?

Peter

wxie Is there anyone interested in trying this game?

Yeah. I am. My interest is not so much the genre (Breakout-like game) but the fact that it uses Scheme. But probably not today.

Greetings
Peter

ffaf

(list-set! ((0 0 32 12 100 0 0)) 0 (0 0 32 12 100 0 0))

this feels extremely weird, parentheses are there in Guile to “evaluate”, so you are effectively evaluating the first list twice? This works instead:

scheme@(guile-user)> (list-set! (list 8 0 32 12 100 0 0) 0 (list 0 0 32 12 100 0 0))
$2 = (0 0 32 12 100 0 0)

If you need more help we can go through this together.

wxie

ffaf

Thank you for help.

I thought the code should also working:

(let ((frames (list-ref source 1)))
(list-set! frames 0 (list x y w h 100 0 0))))))))

Why is it not? This is my question and I think this is the error.

wxie

ffaf
Do you have any clue about how to fix this?

Peter

I installed guile-3.0-dev on my Xubuntu Linux. But I get this error:
configure: error: can't find guile. This software REQUIRES guile.

wxie

Peter
You may need
#+BEGIN_SRC shell
aclocal
./bootstrap
#+END_SRC

The bootstrap file is

#!/bin/sh
# Initialize the build system.

set -e -x
exec autoreconf -vfi

The configure.ac file should have the following

# Check for latest Guile development files.
GUILE_PKG([3.0 2.2 2.0])

# Checks for programs.
GUILE_PROGS
GUILE_FLAGS

Let me know if you still have problem.

Peter

At the end of the code you showed seem to be way to much parentheses. If I counted correctly there should be three closing parentheses.

Greetings
Peter

wxie

Peter
You are right. I just copied part the closure. The rest is not related.
Do you have problem with it?

Peter

I was a bit naive and thought the parentheses at the end were causing your problem.

(let ((frames (list-ref source 1)))

At the risk of being naive again: I don't understand why there are two parentheses around frames etc.

wxie

Peter
I made it work by ugly doing this

          (let ((frames (list-ref source 1)))
            (let ((frame-0 (car frames)))
              (list-set! (list frame-0) 0 (list x y w h 100 0 0)))))

Peter

Ah, I see! frame-0 is the first entry of frames. For the last line ("list-set!") my Scheme knowledge isn't good enough. And is "list" normal Scheme? Or is it Guile-specific?

Anyway, great if it works now.

Greetings
Peter

wxie

Peter
I think (list ...) is common for all lisp.

ffaf

Sorry, I missed the notification for this, happy that it was solved!