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The Slate Programming Language 244

An anonymous reader writes "I know that we have had an influx of new programming languages of late, but I feel that this one merits special attention. Theoretical computer scientists and long-time Squeak and LISP contributors Brian Rice and Lee Salzman have been rapidly developing a language called Slate. It draws on the various strengths of the Self, Smalltalk, and LISP languages. To quote from the website: 'Slate is a prototype-based object-oriented programming language based on Self, CLOS, and Smalltalk. Slate syntax is intended to be as familiar as possible to a Smalltalker, rather than engaging in divergent experiments in that respect.' The beta release is currently being written in Common LISP."
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The Slate Programming Language

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  • Pretty Cool (Score:1, Informative)

    by Anonymous Coward on Saturday March 27, 2004 @01:38PM (#8689540)
    Prototype based, multi-methods.

    Looks like dylan [].

  • why slate (Score:5, Informative)

    by larry bagina ( 561269 ) on Saturday March 27, 2004 @01:48PM (#8689609) Journal
    From the faq: Why did we decide on a new programming language?
    • Smalltalk-80 is over 20 years old. We don't think the original team intended for the model to last this long (well, from discussions on the Squeak [] mailing list, they've said so).
    • Smalltalk [] doesn't adequately express many design possibilities that show up often in good complex programs. Requiring classes, not allowing multiple dispatch, and not including some form of multiple inheritance is limiting for a lot of interesting cases.
    • The Common Lisp [] and Dylan [] communities have created some powerful interface toolkits which Smalltalk cannot easily take advantage of.
    • Cecil [] is statically-typed and not very dynamic. Dylan [] suffers from a case of too much syntax, and not enough emphasis on live environments.
    • Common Lisp [] is not object-centered or generic enough with its functions.
    • Goo [] uses the unfriendly Lisp syntax, and isn't quite suited to object-centered thinking.
    • Self [] turned out to be too strange an environment for Smalltalkers, and never had a decent implementation. Strongtalk [] was bought up.
    • Bytecode virtual machines and chunk format are old hat. It'd be worth at least trying some different run-time setup.
    • The Squeak [] system is very powerful in terms of some experimental libraries and user interface ideas, but is based on an aging architecture and a license that is partly troublesome.

    i think smalltalk++ would be a better approach than inventing a new language. Look at C++: it's backwards compatable with C, so a C coder is already a C++ coder and can slowly start making use of new C++ features.

  • by Deraj DeZine ( 726641 ) on Saturday March 27, 2004 @01:49PM (#8689617)
    That link has an awful lot of plus signs. As if you're trying to hide something on the end of the URL. But what could it be? Maybe if I clic---No! Ow! My eyes!

    I can't believe they changed the layout.
  • PLEASE DISREGARD. (Score:1, Informative)

    by Anonymous Coward on Saturday March 27, 2004 @02:28PM (#8689850)
    I am one of the primary authors of Slate and I *DID NOT* authorize anyone to do such advertising as this (and I believe the post is severely misleading on other levels), as we are CLEARLY not ready for any sort of exposure of this level. Unless you are really specifically interested in an essentially unuseable language, move along and ignore this. Again, move along and ignore.
  • by Jecel Assumpcao Jr ( 5602 ) on Saturday March 27, 2004 @02:40PM (#8689938) Homepage
    When running a program, it is very likely that you will want to create new objects as you go along. You have some alternatives:
    • call a magic constructor fucntion (C++ and friends)
    • send a message like "new" to a factory object (like a class in Smalltalk)
    • send a message like "copy" or "clone" to an object that is like the one you want to create

    In the third case you might find out that you can get by with a set of "prototype" objects to copy from and you don't need classes at all. But to actually eliminate classes you will have to find solutions to the other things they do for you like hold the behaviors for the objects (you can put them in the objects themselves, for example) and reflection (Self uses special "mirror objects" for that).

    There are several different styles of prototype based languages [].
  • by Chinju ( 662523 ) on Saturday March 27, 2004 @03:20PM (#8690160)
    I don't know much about Slate, or Smalltalk, or anything, for that matter, but a quick look at the article shows that both of your "confusing" examples are not that confusing...

    As someone else already pointed out, "3 + 4 * 5" ==> 35 (not 23) because Slate has no differences in binary operator precedence and therefore always associates to the left.

    And as for "(3/4) == (3/4)" ==> false, this is because "==" tests for _object_ equality, and the two different instances of "(3/4)", while representing the same numerical value, are distinct objects. It appears that "=" tests for numerical equality.
  • Re:Obligatory. (Score:5, Informative)

    by 11223 ( 201561 ) on Saturday March 27, 2004 @03:32PM (#8690221)
    Sure. I'm not good of thinking of Haskell and Smalltalk examples, but since I know Lisp, I can throw out a few. If you've:
    • Played Jak & Daxter or any of its sequels
    • Played Abuse
    • Booked a reservation on Orbitz
    • Visited the campaign web sites of Bill Clinton in '96 or Howard Dean in '04
    • Used the Mirai facial-animation software or watched Gollum in Two Towers / RoTK
    • Used an AMD processor, parts of whose logic is validated via the ACL2 [] theorem-prover software
    • Used GNU/XEmacs
    • Used AutoCAD
    • Used the lisppaste [] pastebot on a bunch of channels on Freenode
    You've used or seen a program that was written in a Lisp variant (all but Emacs and AutoCAD were done in ANSI Common Lisp). To find out more, visit CLiki [].

    Not all the world is a desktop application with a GUI. Lisp and the other languages aren't going away in this space anytime soon. It's just too cumbersome to do many of these things in C++, and too slow to do them in Java (Common Lisp is usually native compiled).

  • Objective C (Score:3, Informative)

    by Doug Merritt ( 3550 ) <> on Saturday March 27, 2004 @03:58PM (#8690368) Homepage Journal
    Oh, I can't think of any other language that used smalltalk as a base... Oh yeah, except C++.

    Objective C borrows both syntax and semantics from Smalltalk (on top of C itself, of course). It's a nice small language.

  • Re:Obligatory. (Score:3, Informative)

    by 11223 ( 201561 ) on Saturday March 27, 2004 @04:09PM (#8690436)
    Here you go [].

    Your use of parentheses there is amusing and sad. You do know that those parentheses denote serialized lists, right? You've just made a list of a list of a list of a ...

    Sheesh, learn a little about the language before you go making fun of it.

  • NewtonScript? (Score:4, Informative)

    by Archibald Buttle ( 536586 ) <> on Saturday March 27, 2004 @04:20PM (#8690489)
    Yet another language turns up that claims its virtual parents are SmallTalk, Lisp, and Self...

    It would seem that Apple may have had it right ten years ago when they made NewtonScript, the native language of their Newton computers, since that language too claimed SmalllTalk, Lisp and Self as its antecedents.

    Having had a brief look though at the documentation for Slate, and yesterdays Prothon, I can't help but feel that Apple did a much better job with NewtonScript and the Newton environment. NewtonScript seems to me to be much more mature and better thought out than these two examples.

    As for comments that I read here about prototype-based languages not being suitable for application development and are effectively only the domain of accademics, I say bullshit. Class-based programming really isn't the only method of OO development, and prototypes can be equally effective. Many thousands of applications were written for the Newton, and they all used NewtonScript and its prototype-based object model. Prototypes can usually be used in a very similar way to classes, and most class-like behaviour can easily be simulated.

    If you're interested in finding out more about how NewtonScript worked and functioned there reference manual can be found here: ntation /NewtonScriptProgramLanguage.pdf
    For a discussion of prototype vs. class based programming consult Appendix C of the NewtonScript reference manual.
  • Re:Deja vu (Score:4, Informative)

    by angel'o'sphere ( 80593 ) on Saturday March 27, 2004 @04:23PM (#8690506) Journal

    What's a "prototype-based object-oriented" language and how does it differ from C++ and Java?

    In Java and C++ you have classes. In a prototyped language usually not, there you only have objects.

    To make it simple, lets look at the java.util.Hashtable.

    Suppose if you write this:

    class MyClass {} the compiler would do this:
    Object MyClass = new HashTable();

    So, instead of defining a class, you just created an empty object ... I used a Hashtable, because that makes the later explanations more easy, it could have been simply an object of course.

    So far your class has no properties ... no data and no methods.

    So you likely would write something like this:
    class MyClass {
    Object start;
    Obejct end;

    As prototyped languages are usually typeless you would only need to write this:
    class MyClass {

    Our hypotetical compiler makes this from your typed code:
    Object MyClass = new Hashtable(); // define a "new class"
    MyClass.add("start", null);
    MyClass.add("end", null);

    So, instead of "defining" a class, like you did in Java or C++, you only created an object in the most global namespace. That object is called "MyClass" just as your class would have been called.

    That object has two "slots" with the names "start" and "stop", just like a class would have two attributes of type Object.

    So: the concept is called prototyping, because you would usually initialize the MyClass object more properly, so that "start" and "end" would have a value and would not be empty.

    Now comes the interesting point: we know how to make classes now. How to make objects from them?

    Well, all Objects have a method called "new".

    In java you would write new MyClass(). But you could of course asume a class had a static method called NEW().

    So MyClass.NEW() would create a new object of type MyClass. That method is usualy build into the language and every "class" has it. So, what does NEW() do? It "clones" the object MyClass.

    In Java we have a class MyClass, and with new we create objects. The objects have some kind of poitner to their class.

    In a prototyped language you only have objects. If you say new to them, they simply create a clone from themselves. The original object is called "prototype" or "traits". Instead of calling a constructor to initialize such a new created object it is fully initialized with default values during teh cloning.

    Why did I use a Hashtable as example? Well, you simply can tell a Hashtable to clone itself ... if the Hashtable describes a prototype. The slots in a Hashtable are similar to teh slots in an object of an prototyped language. Suich a slot usualy has a name and can hold any object ... methods are objects as well :D

    You can merge objects ... and so you do not only get a new object but also a new "class". Thats one way how inheritance could be implemented. But usualy you use nested Hashtables for inheritance, as yoou most often want single inheritance only .. and merging is used for mixins .... another term wixh would need an explanaition as long as this one.

  • by alienmole ( 15522 ) on Saturday March 27, 2004 @06:33PM (#8691353)
    There does seem to be a fair amount of interest in prototype-based languages lately. Javascript's object system is also prototype-based, also inspired in part by Self, as well as Lisp/Scheme. Javascript may have helped trigger the current wave of interest in this subject.

    Purely prototype-based languages don't really compete with their more structured (class-based) cousins, though. One of the main benefits of prototype-based langauges is that they give a lightweight way to create an abstraction - you don't necessarily have to create a class first. This isn't necessarily a pure win. The structure provided by classes can be useful, too. A good language should provide both capabilities, no matter what mechanisms it uses to do that. It's possible Slate does this, I haven't looked.

    Another good candidate mechanism for lightweight abstraction is first class anonymous functions, i.e. lambda, as found in Scheme, Lisp, Javascript, Perl (Python got it wrong, unfortunately). Having real lambdas tends to eliminate a lot of the problems which other languages find themselves trying to solve. Although it helps to also have macros, which limits the list to Scheme and Lisp.

  • by Decaff ( 42676 ) on Saturday March 27, 2004 @06:59PM (#8691501)
    It would. A common mistake in Java is to try and compare Strings using == e.g.
    if (a == "value")
    instead of
    if (a.equals("value"))
  • by water451 ( 200460 ) on Saturday March 27, 2004 @07:30PM (#8691666) Homepage

    This took me by surprise, and I'm not a usual poster here, so I don't have the energy to reply to each person in turn. So I'll summarize some points I've seen:

    This post is entirely misleading; we are not researchers, and we do intend to do business based on this language. However, what the language itself is is entirely mis-represented. Note: the original submitter is not affiliated with our project in any way, and in fact does not actually know or use the language.

    First, we are not in a project mode of self-promotion or public representation at all. Nothing on that site claims to be a real tutorial, and the current efforts have mostly been about experimentation. We are still preparing the really usable implementation, and have a huge set of ideas and environment enhancements in backlog waiting for this. What's mentioned on the front page is actually a mere fraction of what we're working on.

    The project name, "Slate", is short for "Clean Slate Smalltalk". If you don't know Smalltalk, very little of it will make sense; what's at issue is that we mean what Alan Kay would say in that Smalltalk currently means Smalltalk-80, just a certain quirky snapshot of a whole range of ideas that he and others were working on. We're interested in that whole range.

    Slate is only about prototypes insofar as this was an initial language stage that was simple to play with and powerful enough to explore without too many limitations. Further revisions of the language will feature higher-level facilities for more type-safe programming and more declarative consistency (declarative in the sense of (re-)defining a class and having its instances track that consistently).

    Slate's environment is about 0.001% of completion of what we intend, and we have a huge body of experience and code and ideas to draw upon which are already largely mapped-out. What you see on the site is not representative of what we want in those terms.

    The syntax is definitely odd. At issue is the fact that we kept a minimal Smalltalk syntax core and optimized it for "phrase value" and added various annotation mechanisms, which wind up being very hard to understand until you crack open the 40-page programmers' manual which explains this all. Although it is no tutorial, everything is explained there, and improved with feedback from early users.

    Slate is eventually going to be a full environment, and be very flexible at a large scale, so that questions of prejudice about design choices will not matter, because we actively take part in designing the system so that users can make the choices: whether image-style live interaction or C-embeddable, highly-optimized, low-overhead, no-IDE deployment. And make it so you can make these choices independently; current Smalltalks, Lisps, Dylan, and hundreds of other languages (especially the more common ones) don't have this.

    There are a number of issues brought up here which are addressed but not advertised on the front page; for example, Slate will handle security at the language level, using capability analysis and the subjective programming feature mentioned. Our project has no marketting team (see Smallscript), and has actively avoided public claims until we have the demonstration at-hand. I am giving a presentation and demonstration of the next major release, featuring a self-hosting (C-friendly) setup in Seattle at Smalltalk Solutions 2004 [] in May.

  • by ingenuus ( 628810 ) on Saturday March 27, 2004 @07:32PM (#8691677)
    If your methods are associated with prototype objects, then if you have existing non-prototype objects and change a method, then would the non-prototype objects get the method def passed down, or what?
    Your use of the term "(non)-prototype object" is a bit confusing since every object is a "prototype" which can be cloned... but I think I understand your question.

    In prototype-based languages, creation of new objects occurs by copying (cloning) existing objects. After copying, the clone is independent from the original -- changing one has no effect on the other (there is no Inheritance relationship between them).

    Inheritance-style call (message) dispatch is handled through a slot named "parent" that every Object has. A call (message) that does not have an object-local slot (handler) is deferred to the objects referenced in the parent slot. In this way, objects can share the same parent and thus the same behaviour (unless locally overridden).

    Note that when a clone is made, all slots in the original are copied to the clone, so the clone has the same parents as the original. Of course, after cloning, you can change any of the clone's slots independently from the original, including the "parent" slot.

    Prototype languages are really not much different from class-based languages... they just split up the responsibilities a bit differently (and perhaps more uniformily).
  • by jeti ( 105266 ) on Saturday March 27, 2004 @09:21PM (#8692330) Homepage

    You read right. JavaScript has a prototype based system for objects. I seldom see this mentioned in language design discussions.
    Actually I like JavaScript and it's prototype system quite a lot. It's a nice and powerful little language.
    But that's likely only the case because I never needed to implement any cross-browser stuff in it.
  • GNU Smalltalk (Score:3, Informative)

    by hak1du ( 761835 ) on Sunday March 28, 2004 @06:59AM (#8694857) Journal
    If you are looking for a Smalltalk-like language for scripting applications without the Smalltalk GUI, check out GNU Smalltalk []. It's a pretty faithful implementation of Smalltalk, and it even has a JIT.

!07/11 PDP a ni deppart m'I !pleH