World: r4wp

Luis, the Red Java bridge will be able to call generic Java code, 
so it should be possible to use the App Inventor library

Looking at the current bridge.red, It seems that the return value 
of  a called a method of a Java object is treated as an integer by 
the bridge. Am I correct in thinking that is fine for integers and 
references to Java Objects? I presume logic! will be okay too (if 
caste back ) .


I guess that the bridge doesn't support string or float values yet.

It does in the new bridge version I'm about to push online.

I just need to make some addition to the Red/System compiler before.

That's great news.

Are there any tutorials on how to write programs using Red?  (Not 
Red/System - I know where the documentation is for that.)

What I mean is something like Rebol in 10 steps, but maybe Red in 
10 steps (assuming you already know Rebol).

For instance, I try to compile and run the following simple script:

Red []

img1: load %img1.jpg
print img1

When I run it, I get the following error:

*** Error: word has no value!
unset

I know that Doc says Red isn't ready for general use yet, but I was 
wondering if maybe there were some resources so I could get started 
getting up to speed on it.  When I started learning Rebol, it was 
probably even less complete.

Yeah, Larry Wall bashed it for that

Larry Wall used quite unrelated (and mostly invalid) arguments

No tutorials, though, but there's a fair amount of example code. 
It currently relies on being able to use a lot of REBOL knowledge

The best thing is to program as basic as possible, and always be 
on the watch for missing stuff. For example, LOAD only works on strings, 
and there's no type checking, so it probably used the string value 
of %img1.jpg

With my I/O bindings you can READ a file and then LOAD it, but only 
UTF-8 text

Now that Red/System can read binary files, I could make a facility 
in Red, but it would have to do without a binary! type. I could return 
a handle to low level memory as an integer!

However, there would currently be no facilities to access the content 
at the Red level, so you would have to pass it to Red/System functions 
to do anything with it

REBOL is almost completely made from C! Sometimes hard to follow 
where and how things come together. So happy Red comes to the Redscue.

Can a function be overloaded in Red? Example do-this: function [input 
[integer! c-string!]][either type? input [do-one][do-other] ]

That's not overloading, that's just a conditional

Real overloading is possible in the compiler, but there's currently 
a bug in the interpreter that always makes it use the first function 
definition. This is fixed, but not yet in the master branch

do-this: :do-one

do-this: :do-other

I ask this obviously because I want to replicate the REBOL behaviour 
of the random function that takes different arguments like random 
"abcdef" shuffeling the string; random 1.0 giving a random real between 
0 and 1; random 6 giving an integer from 1 up and to 6. 

So in a sense I need a return type that differs too. REBOL (R3) solves 
this as far as I understand it by returning the pointer to the value 
(and somehow the type of the variable).I ask this obviously because 
I want to replicate the REBOL behaviour of the random function that 
takes different arguments like random "abcdef" shuffeling the string; 
random 1.0 giving a random real between 0 and 1; random 6 giving 
an integer from 1 up and to 6. 

So in a sense I need a return type that differs too. REBOL (R3) solves 
this as far as I understand it by returning the pointer to the value 
(and somehow the type of the variable).

That is twice the same sorry for that! AltMe hung up on me and I 
pasted overenthousiasticly.

You don't need overloading for that, just type conditionals. REBOL 
uses those all the time, and so can Red

REBOL and Red don't have pointers. What you're talking about is a 
Red value the type of which is always known at runtime

So you can always check the type of a value, and you can return a 
value of any type

Some languages dispatch a function to multiple implementations depending 
on the types of its arguments, but that's multiple dispatch, not 
necessarily overloading

Hey invalid Red program if I #include a reds program? Complaint about 
/System
*** Syntax Error: Invalid Red program
*** line: 1
*** at: {/System [^M

Red is not Red/System, is it?

Expected this to be no problem at all. Just not the other way around. 
I feel tutorial stuff coming up.

To write Red/System within Red, you need to enclose it in

#system-global [ ]

seen that before. Had no clue what it was for.

It's usually me who uses it, and it usually #includes Red/System 
files :-)

I guess Red #include could be made to inspect the type of the file, 
and add an implicit #system-global [ ] if it's Red/System

Thank you it compiled. Now I have to find out what this means
*** Error: word has no value!

*** Script error: action 42 not defined for type: 2
logout

That depends on what you're doing

That would be a nice improvement indeed as the file extension is 
reds and the header is Red/System

Apparantly action 42 ;)
sorry bedtime now for me.

Hello2 working on Nexus 7 - Great job Doc. I have to hit the "DO" 
button twice to see a result but it works.

I have this bit of Red/System code that I wrote, but for some reason, 
it just closes the console window.  So I don't know if there is an 
error, and if there was, how would I debug it?

#include %../C-library/ANSI.reds

img1: as-binary 0
size1: 0
img2: as-binary 0
size2: 0

img1: read-file-binary "img1.bin" :size1

print-line img1
print-line size1

print-line as integer! img1/1

img2: read-file-binary "img2.bin" :size2

print-line img2
print-line size2

img3: as-binary size1

i: 0
until [
	i: i + 1
	img3/i: img2/i - img1/i
	i = size1
]

write-file-binary "img3.bin" img3 size1

until [no]

Generally speaking, I drastic approach is to comment everything out 
and gradually uncomment lines until you find the place where the 
problem gets introduced.

And or adding lines where you print information to the console

print [" before call to read-file-binary, size of size1: " size1 
lf]

write-file-binary has a logic! return value
write-ok: write-file-binary "img3.bin" img3 size1

And even try to initialize img3 by 
img3: read-file-binary "img2.bin" :size2

that way img3 can be subscripted like img1 and img2, not sure now 
about your as-binary from integer what you have now.

I am not familiar with Kaj's Libraries but I searched ANSi.reds and 
the Red/System runtime to try to find where as-binary is defined. 
I guess it must be in one of Kaj's other libraries.


I noticed the ANSI.reds includes %common/FPU-configuration.reds but 
couldn't find that in Kaj's Repo. (It doesn't sound as though it 
would include a definition of as-binary though).

Though if as-binary is not defined, you would definitely get a compilation 
error.

Do you get any output from the print statements ?