The Red Programming Language

by Immortalin • 12 years ago

102 38 12 years ago

networked2• 12 years ago

The thing I find the most fascinating about Rebol and Red is their respective type (runtime tag?) systems, which are unusual for modern dynamically typed languages; today you'd expect such things as URLs and file paths to be represented in the language as either plain old strings or classes, not their own basic types. You can see Rebol's and Red's type systems at http://i.imgur.com/0XFuRmS.png (this is a slide from a presentation deck on Red's about page) and http://www.rebol.com/docs/core23/rebolcore-16.html respectively.

riffraff• 12 years ago

I think the word you're looking for is "literals", i.e. rebol has URL literals (cause there isn't much difference in many modern languages between "basic types" and classes).

I always found that fascinating too.

networked2• 12 years ago

You are probably right. The distinct literal notation for the datatypes (which is what the Rebol manual calls them) is their biggest draw for me.

Although the sequence! and the object! datatype in Rebol are not subtypes of each other they have similar semantics (pass by reference, explicit copying, mutation performed in place by built-in functions like sort).

Objects in Rebol and their literal representation are actually pretty interesting, too. Douglas Crockford cites Rebol as one of the inspirations for JSON, and you can see why when you look at an example:

    >> example: make object! [
        var1: 10
        var2: var1 + 10
        var3: now/time
        set-time: does [var3: now/time]
        calculate: func [value] [
            var1: value
            var2: value + 10
        ]
    ]

    >> print mold/all example ; mold/all serializes data
    #[object! [
        var1: 10
        var2: 20
        var3: 21:42:34
        set-time: #[function! [][var3: now/time]]
         calculate: #[function! [value][
            var1: value 
            var2: value + 10
        ]]
    ]]

I haven't read much Rebol application code but as far as I understand serializing objects and storing them on disk as plain text is the norm for configuration and persistence.

qznc• 12 years ago

Most languages have a URL and File/Path class/struct wrapper. Where is the difference?

StevePerkins• 12 years ago

I'm not familiar with Red, but my understanding of REBOL is that its main use case is writing domain-specific languages to do the actual work. I can think of many domains in which you would want your DSL to include primitives/literals for files or network URL's.

Of course, if Red is not so much a DSL as it is a DSL-authoring language like REBOL, then I share your confusion. For a general purpose language, I'm not sure what the advantage would be of making those primitives/literals rather than components within the standard library.

jdeisenberg• 12 years ago

As wonderful as the language might be, the site is nearly unreadable; the black background makes the dark red links almost invisible, and it "swallows up" the thin, small white text.

dockimbel6• 12 years ago

I have replied about the web site on the top comment. I have noticed that the readability varies greatly across browsers/OS/devices. Anyway, the color scheme and layout we are using currently are far from being the best. We will change that before officially opening the doors to our guests. :)

draegtun2• 12 years ago

It has been mentioned before and there have been redesign options put into the mix - http://red.reb4.me

gaius• 12 years ago

Not to be confused with http://en.wikipedia.org/wiki/Core_War#Redcode

soapdog2• 12 years ago

Does anyone has a link comparing Red to REBOL? I was a heavy REBOL user back then and always missed the language. I wonder if Red is a viable substitute...

doublerebel2• 12 years ago

From my reading today it seems REBOL 3 and Red have semi-merged [1]. REBOL 3 extensions can be written in Red, and the communities seem to share the same online spaces and goals.

Red looks awesome in the long run, the main weirdness being its refusal to follow standard math operator precedence [2].

Although Red's macro/DSL buildup skips a ton of intermediate bloat, someone needs to write a normal server framework to interact with standard industry data sources. When it becomes easy to add a Red microservice to an architecture, Red can enjoy an explosion of adoption as Go has.

[1] http://rebolforum.com/index.cgi?f=printtopic&topicnumber=27&...

[2] http://stackoverflow.com/questions/26514041/fixing-the-rebol...

soapdog2• 12 years ago

Thanks a lot for the links and reply :)

akavel• 12 years ago

Um, the first link seems to me to only suggest unification of REBOL 3 and Red tests, not languages themselves; or do I miss something? Also, it seems to only suggest that, not claim it done yet?

iArnold• 12 years ago

As the person that replied to your second point on the SO question there, I have to add something here. There are other calculators made in Rebol. (Search rebol.org site scripts for those). Having this calculator adapted for the math operator precedence would be too farfetched, for the example merely shows how much can be done with so little code. The other is that I do not have the ultimate say in what Rebol and or Red should do with math operator precedence, I have nothing to say about that to be exact ;-) (I am free to express my opinion on the subject). What I state there still holds for me, the operator precendence is imho arbitrary, and not necessary at all, counterintuitive for kids, and (I am a mathematician) the world can do without these rules. With operator precendence I have no other choice then to use ellipses when I have 3 * 4 + 1 and I meant I wanted to add 1 to 4 before multiplying by 3: 3 * (4 + 1) in Rebol I can write 1 + 4 * 3 and I do NOT have to use "(" and ")" to achieve what I intended saving me four keystrokes.

Regards,

Arnold

dockimbel6• 12 years ago

You will find in Red everything you liked in Rebol, with some important additions like cross-platform static compilation and system programming abilities [1] through the built-in Red/System DSL. On the downside, Red is still alpha, but beta is just a few months ahead.

[1] http://static.red-lang.org/red-system-specs-light.html

ajkjk2• 12 years ago

This site should really have some code examples on the main pages. I shouldn't have to watch videos to get a basic idea of the syntax and what it can do. The blog on the front has some code, but it's not geared towards explaining the basic ideas.

dockimbel6• 12 years ago

Red's author here. I agree and I apology for the currently poor web site. It was built for the Red and Rebol crowd to help them follow us while we are building Red. As we are getting closer to a beta version, we are planning to move in the next couple of months to a brand new site that will properly communicate about Red to newcomers.

About the syntax and semantics, in a nutshell, it's a Lisp without parentheses and with infix operator support. Tokens are separated by a whitespace or a delimiter (very few of them). Code is a tree of lists (called "blocks" in our local jargon), blocks are delimited by square brackets [].

You can have a look here [1] for a larger code and syntax example.

[1] https://github.com/red/red/blob/master/red.r

ajkjk2• 12 years ago

Awesome, thanks.

leke• 12 years ago

Good to see you have serious plans for this language. I was always interested in Rebol, but never became any 'good' at it --- although I always like to read updates about it and its forks.

FreeFull• 12 years ago

    red>> .1 + .2 + .3 = .6
    == true
    red>> .1 + .2 + .3 - .6
    == 1.110223024625157e-16

This doesn't feel right to me. I usually would expect equality to be a strictly exact thing. This is bound to cause some problems in code that assumes IEEE-754 has been implemented exactly.

geographomics• 12 years ago

The language distinguishes between equal and "strictly equal":

    red>> .1 + .2 + .3 == .6
    == false
    red>> .1 + .2 + .3 = .6
    == true

I'm not sure if that syntax is the wisest choice, but in the absence of arbitrary precision arithmetic it seems a very good concept, to avoid common IEEE-754 surprises.

They appear to be implementing it along these lines: http://randomascii.wordpress.com/2012/02/25/comparing-floati...

draegtun2• 12 years ago

It should be noted that Rebol comes with an arbitrary precision (bignum) arithmetic option via it's money! datatype - http://www.rebol.net/wiki/Money

  >> .1 + .2 + .3 
  == 0.6000000000000001
  
  >> type? 0.1    
  == decimal!
  
  >> $.1 + $.2 + $.3
  == $0.6
  
  >> type? $0.1
  == money!

Red will most likely get this soon but perhaps with a different nomenclature (Red as already renamed decimal! to float!).

qtxie• 12 years ago

It also doesn't feel right to me when I learned it for the first time. But if you know that "=" means "almost equal" when doing float comparision, it is very convenient in practical use. For example, if we want to compare two float variables. In Red:

  if float-1 = float-2 [
      ; do something
  ]

In other languages:

  if (float-1 - float-2) < EPS {
      // do something
  }

Obviously, Red's way is more natural and readable. :)

fulafel• 12 years ago

Choosing the epsilon requires numerical analyis expertise or lucky cargo-cuting: https://randomascii.wordpress.com/2012/02/25/comparing-float...

darkoverlord• 12 years ago

I am happy to read that the site will become more accessible to a larger group. I've REBOLed a long time in the 2000s and made good money of it.

Make no mistake: both REBOL and RED have an extremely powerful underlying model model to help solve problems. In a world of containers and micro-services "something like these" will emerge.

If nothing else, that's a reason to follow them - between Go and RED/REBOl you can see a glimpse of computing as it will be.

johnk-• 12 years ago

Another place to learn more about Red and Rebol is over at the stackoverflow chat room. http://chat.stackoverflow.com/rooms/291/rebol-and-red

The Red Programming Language

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