REBOL Technologies

Carl's REBOL Blog - Vive la REBOLution

Carl Sassenrath Carl Sassenrath, CTO
REBOL Technologies

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6984729 visits since 12-Mar-2007



A few words from REBOL's architect.

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REBOL 3.0 Front Line

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Recent Articles:

25-Feb-2018 - Website update, new projects, fresh thoughts [0554] 8 Cmts
30-Jan-2016 - CGI requires content-length [0553] 1 Cmts
24-Jan-2016 - Linux 64 bit Rebol/Core test release [0552] 20 Cmts
17-Jan-2016 - Rebol 2.7.8 released for ARM v7 [0550] 10 Cmts
10-Jan-2016 - Website server software changed again [0549] 1 Cmts
26-Dec-2015 - Testing 1, 2, 3 on new web server [0548] 15 Cmts
8-Feb-2015 - back up [0547] 5 Cmts
29-Dec-2014 - Embedded system performance comparison [0546] 4 Cmts
29-Nov-2014 - Bad face in screen pane - what a pain! [0545] 60 Cmts
29-Nov-2014 - Web site moved [0544] 1 Cmts
15-Feb-2014 - Localized FUNCTION and CLOSURE definitions accepted [0543] 7 Cmts
Contents- Index of all articles.

25-Feb-2018 - Website update, new projects, fresh thoughts [0554]

Rebol website home page has been updated with a few announcements and a new Rebol Projects page has been added. Take a look if you have a chance. I'm also looking for help with some of it, mostly small tasks like better CSS or how to build OSX on cloud servers. (Hopefully that's a small task.)

Having been away from Rebol for several years and working at a fantastic consumer electronics company on cool projects, you may be asking yourself: what is my interest in Rebol at this point? Honestly, I still love Rebol, and I continue to use it for what I think of as "hobby" projects. For me it's kind of like making wine, handling ranch tasks, fiddling with ham radios, or pondering/proposing electro-magnetic theory. I never stop thinking about them, but they take a back seat to my pay job.

Yes, I know that Rebol has forked several ways. What's my view of that? I see it as mostly positive. There many good ideas and serious progress being made. People want progress. Many of these ideas reflect my own desires for the future of the language. Those who use and depend on Rebol know what they want from language technology. I'm no exception from that.

I'll be saying more about my interests, and what I've learned about myself in recent years in the world of commercial products and technologies. A lot of what I learned is just practical insights, like focusing on getting products done. But, those lessons are mixed-in with some big-dream projects. I keep thinking about those those moon robots that someone once suggested would be made possible with Rebol. I like that kind of thinking... those big bold ideas.


30-Jan-2016 - CGI requires content-length [0553]

I've noticed that various Rebol CGI website scripts hang. Apparently, HTTP POST on newer servers (or clients actually) keeps the socket open in such a way that the standard read-cgi function hangs.

The fix I use in newer scripts is to use the CGI content-length field to terminate the read.

If you have insights into this problem, please comment. I'd like to fix read-cgi in the next release.


24-Jan-2016 - Linux 64 bit Rebol/Core test release [0552]

Released a preliminary (alpha test) version of Rebol/core for 64 bit Linux. This was built on a Ubuntu system, and I'm not entirely sure how portable it is, but maybe you can give it a try and post your comments here?

Side note: motivation for this release was moving to a 64 bit cloud server.


17-Jan-2016 - Rebol 2.7.8 released for ARM v7 [0550]

I've released ARM v7 versions of rebol/core and rebol/view in the download pages of this website. I use these mainly on Odroid boards, so I thought other rebolers might want to give them a try. They're pretty much untested; I don't have a lot of time for that. You'll need to watch for problems. Let me know how they do. I've not tried it with Raspi or Beaglebone yet.

You can post comments here or send me a message via feedback.

Side note: As I've mentioned before, I like the Odroid XU3 and C1. The XU3 has 8 CPU cores, and I'm using it right now to write this blog page. I use the C1 for home control. You can find out more or order a board to play with from reboler Bo's store at


10-Jan-2016 - Website server software changed again [0549]

The Rebol websites went down last week due a core dump in the new server software, and the most recent update failed to run CGI scripts.

As a result we've changed our web server software again. For, most features should be up again. still needs some work.


26-Dec-2015 - Testing 1, 2, 3 on new web server [0548]

Tap tap tap. Does the Rebol blog work again? Let's see.

Really, just kicking back on a holiday to have some fun bringing back on a new web server. Amazingly, the old hosting site was good for more than a decade, and I take my hat off to them, but the cloud has become cheaper and more powerful when it comes self-operated websites.

Anyway, there are quite a few scripts here to either update or remove. I'll be working my way through them. And yes, I know needs work also. But, one thing at a time.


8-Feb-2015 - back up [0547] website is back up. Credit card had expired, and Bo L. brought it to my attention. I wonder if it would make sense to move to the same cloud server as What do you think?

PS: If you see any other servers go down, don't hesitate to point them out. Thanks.


29-Dec-2014 - Embedded system performance comparison [0546]

Last week I found a new Odroid C1 board under the Christmas tree. Curious about the performance of the new board, I decided to compare its speed to a few other embedded SoC boards I've got around the house, including the Raspberry Pi, Beaglebone Black, and Odroid XU3 Lite.

I often use the Rebol speed? function to get a rough idea of the performance of desktop and server systems, and it works equally well for embedded devices. The measurement method is pretty simple, but I've found it provides an accurate estimate.

Here are the prices (plus|minus and for boards only), speeds, and Rebol speed? results. For reference, I included my old Ubuntu 10 Linux desktop (Intel i5).

Board Price CPU MHz DDR MHz Eval CPU Mem
Raspi $40 700 400 369 130 7
BBB $45 1000 800 720 437 16
Odroid-C1 $35 1500 792 1040 615 15
Odroid-XU3-L $105 2100 933 3020 1474 62
Intel i5-2500 $500 3300 1600 8000 4200 118

Using the Raspberry Pi as the base, the table below shows the improvements as simple multipliers (X times). The CPUC (CPU clock speed) and DDRC (memory clock) are combined to obtain the HW "boost" labled as X Factor. This is overly simplistic (e.g. ignores bus width) but the results seem to be in the ballpark.

Board X Eval X CPU X Mem X CPUC X DDRC X Factor X Price
Raspi 1.00 1.00 1.00 1.00 1.00 1.00 1.00
BBB 1.95 3.36 2.29 1.43 2.00 2.86 1.13
Odroid-C1 2.82 4.73 2.14 2.14 1.98 4.24 0.88
Odroid-XU3-L 8.18 11.34 8.86 3.00 2.33 7.00 2.63
Intel i5-2500 21.68 32.31 16.86 4.71 4.00 18.86 12.50

Taking the above into account, the speed? results can be divided by the X factor. A result of 1 would tell us that the Rebol speed perfectly matched the HW boost. Numbers less than 1 fell below expectations. Greater than 1 exceeded.

The final column shows the bottom line, the performance (for Rebol eval results) for the price. Both Odriods are at the top, with the new C1 in first place, and the XU3-L not far behind.

Board Eval/HW CPU/HW Mem/HW Eval/Price
Raspi 1.00 1.00 1.00 1.00
BBB 0.68 1.18 0.80 1.73
Odroid-C1 0.66 1.11 0.51 3.22
Odroid-XU3-L 1.17 1.62 1.27 3.12
Intel i5-2500 1.15 1.71 0.89 1.73

I'll update these numbers if any config changes further improve performance (e.g. L2 cache enable, DDR clock adjustment, bus arbiter.)

If you're interested in a nice little computer for special projects, the Odroid C1 makes a good choice. A good place to buy them is at Ameridroid, run by our Rebol friend Bo Lechnowsky.

If you happen to have speed? results for any other embedded processors/boards, feel free to post those in the comments. Be sure to mention the base price for comparison.


29-Nov-2014 - Bad face in screen pane - what a pain! [0545]

When you run Rebol/view 2.7 on some versions of Linux, you might hit this error message:

User error: Bad face in screen pane

That's got to be one of the most annoying error messages ever created. It happens when the graphics init sequence fails for any reason. Most of the time, what it really should be reporting is:

System error: Cannot open default X11 screen font (courier 11)

If your system doesn't have that font size installed, you'll run into the error, and there's not much you can do about it.

I like to use Rebol as a tool on a variety of Linux systems, so I made a small fix today to check for a range of courier font sizes from 10-15. I suppose if all those fail, it should just try to get the font info from any font that is installed on your system.

Now, I just need to figure out a way to publish the fix, sooner not later, and maybe there are a few other critical Rebol 2 bugs that need to be merged in there? Please let me know.


29-Nov-2014 - Web site moved [0544]

The entire website was moved to a newer, faster server recently. Unfortunately, this caused a problem with file directory access, and some pages on the site may not be generated properly. Today I fixed the blog index, but if you find any other pages look wrong, please let me know. Thanks.


15-Feb-2014 - Localized FUNCTION and CLOSURE definitions accepted [0543]

The idea has been around for a while now that Rebol needed a more "closed" environment for functions, where local variables would be implicit rather than explicit. In other words, why put the burden on the programmer of tracking what's a local variable. It's problematic if you're not paying attention.

Rebol version 3 added that feature, but the concept wasn't embraced in the naming. For example, the most obviously named FUNCTION mezzanine, used by many newcomers/beginners, didn't support it. You had to use FUNCT. Not so nicely named. To change the definition was debatable. It's friendlier, but disruptive.

Having taken a long break from Rebol development, I guess these days I'm more in favor of disruption and going down a better path for new users. As I've said many times, Rebol 3 is still in alpha. That means we get to fix stuff and make it better. Sorry if it's a bit disruptive. There are always a few bumps in the development road, but you can be afraid to keep moving forward.

For the record, here's the GitHub pull:

Now, if you think it needs further revision, it's time to submit that. Let's get it ironed out.

And many thanks to BrianH, Ladislav, Andreas, BrianD, and anyone else who is helping to push this along.


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