World: r4wp

Can I pass function pointer as an argument to another function in 
Red/System?

Yes

However, it's not yet supported for functions defined by #import, 
so if you need that, you have to write a wrapper function

Also, in some places you have to cast the function pointer to an 
integer to pass it

Ok, thanks. I unfortunatelly hadn't chance to check Red/System in 
last few months. I'm very glad it can be done, I have to find some 
time for Red/System again.

Since Red needed jump tables, you can also go the other way around, 
and cast an integer/pointer to a function, then call it

Here's the code for the Red GUI IDE:

Red []

#include %GTK/GTK.red

view/title [
	text: area
	button "Do" [
		unless any [
			none? script: get-area-text text
			empty? script
			empty? code: load script
			unset? result: do code
		][
			prin "== "
			probe result
		]
	]
	button "View" [
		all [
			script: get-area-text text
			not empty? script
			not empty? code: load script
			view code
		]
	]
	button "Quit" close
] "Red GTK+ IDE"

Nice! It's amazing how fast you came up with a VID-like dialect for 
Red.

Well, most of the work is in the Red/System layer that I did more 
than a year ago

Same for the other bindings

Plus, when putting a Red layer on top of it, you're staying within 
Red and Red/System, so you're on known terrain. Starting a new binding 
in Red/System throws you into the abyss of the external library's 
C code, headers and idiosyncracies, and documentation that may or 
may not exist or be correct

What can you do for Android where this is no gtk?

It requires a completely extra set of bindings, including to the 
Java VM and the GUI. We're thinking about it

OK.  Say I have a fresh Windows PC and I want to start coding in 
Red/System for the target of Raspberry Pi.  Help me understand what 
I need to do.  Here is what I assume needs to be done, but I may 
be wrong.

1. Download R2, I assume.  Any particular version?
2. Download Red/System compiler.  From where?
3. Write the program on the PC.

4. Compile it with Red/System on the PC, but for the Raspberry Pi 
target.  Is that just a setting somewhere?
5. Move the compiled file to the Raspberry Pi and execute it.

The following should have you covered:
https://github.com/dockimbel/Red#readme

Target for Raspberry Pi is "Linux-ARM".

That's exactly what I was looking for.  It would be great if that 
was prominently linked from red-lang.org. :-)

It is

View for windows, there is a helper script redcompiler.r on rebol.org 
to facilitate (cross-)compiling

Last week Red presentation in The Netherlands, remastered by HostileFork: 
http://www.youtube.com/watch?v=JjPKj0_HBTY

Bas is still couching the presentation together :)

coughing not couching ;)

I implemented compose/deep. With the latest Red fixes, it works now

Is FOREVER not implemented in Red?

If I wanted to access JPG pixel data in Red/System, is there an easy 
way to do that?

As the youngsters say, EPIC!  I just compiled and ran my first Red/System 
program on the Raspberry Pi running Arch Linux.

But I still want to figure out how to access JPG pixel data. :-)

Reading the Red/System Documentation on red-lang.org, I don't see 
any way to access files.  IIRC, someone said that wasn't implemented 
yet?

Bo - R/S is low level - mostly a wrapper to C to enable Red like 
syntax. It will not contain stuff to open files and do more advanced 
things imo, unless you link to some library and create a wrapper 
for such a purpose. I am too eagerly waiting for Red to get more 
advanced stuff. I think, that once Doc finishes the interpreter stuff 
ec., he is back to objects/ports, and then networking/files IO will 
come and more fun begins :-)

FOREVER: not yet supported by the compiler.

mostly a wrapper to C
 Red/System doesn't wrap C, it replaces it. ;-)

:-)

Congrats, Bo

Feels good, doesn't it? :-)

File I/O is available for Red/System in the C library binding:

http://red.esperconsultancy.nl/Red-C-library/dir?ci=tip

There's also standard input for Red there. Further, there's a wrapper 
for full-file I/O for both Red and Red/System that includes network 
I/O through the cURL binding:

http://red.esperconsultancy.nl/Red-common/dir?ci=tip

This gets you reading and writing files, but you have to do any decoding 
yourself. So for reading JPEG data, you would probably write a binding 
to LibJPEG

If it doesn't need to be as specific as JPEG, you could write a binding 
to some wrapper library that supports multiple formats. For example, 
a simple BMP loading function is available for Red/System in the 
SDL binding:

http://red.esperconsultancy.nl/Red-SDL/dir?ci=tip

An example of loading an image is here in PeterPaint:

http://red.esperconsultancy.nl/Red-SDL/dir?ci=tip&name=examples

or xnview command line - then you just need a CALL ....

ah, wrong, I thought that you just need an image info, not actually 
an access to the bitmap data ...

There's also a basic binding to image loading in GDK, so that would 
load you all image types that GDK supports, including JPEG:

http://red.esperconsultancy.nl/Red-GTK/dir?ci=tip

GTK sounds like a winner.

Thanks for all the tips, guys!

For future reference, is it possible to use Red/System for commercial 
products?  Are there any restrictions?