John Carmack working on Scheme as a VR scripting language

Re:John Carmack working on Scheme as a VR scripting language by klibertp on Wednesday July 01, 2015 @01:30PM (#9813595)

The code you pasted is used to illustrate the concepts of ports. You took it out of context. It's not an example of hello world like you're claiming. Also, the code on Wikipedia doesn't always match actual practice of programming in a language..

If you want to see more realistic examples go to RosettaCode, pick interesting task and look for Scheme, Racket and Clojure entries. You can then compare them to each other and to other languages you know.

The other thing is that your code in Scheme and Dart don't do the same thing at all, unless I underestimate Dart semantics very much. A translation of your Scheme code to JS, with as much semantics preserved as possible, would look something like:

    (function (){ // let introduces new scope
      var hello0 = function (){ // hello0 is a variable holding an anonymous function
        return console.log("Hello world"); 
      };
      return hello0();
    })();

That's quite a bit of work less in Scheme, isn't it? But for when you don't need these semantics you can do a translation the other way round (Dart->Lisps). In Racket your Dart example would look like:

    (define (hello) (displayln "Hello world"))
    (hello)

Now, that looks better, right? It's worth noting that the Racket version has only one pair of parens than Dart.

[ Parent | on HN ]

Re:John Carmack working on Scheme as a VR scripting language by klibertp on Wednesday July 01, 2015 @01:55PM (#9813813)

To expand on this a little, here is a thing that you can't translate to most programming languages. By defining a simple, pattern-based macro we can get much closer to the Dart version:

   (func: hello() => (displayln "Hello world"))
   (hello)

All you need to do this - to change the language syntax to look like that - is to write this:

    (define-syntax func:
      (syntax-rules (=>)
         [(_ name (formal ...) => expr ...)
          (define name (lambda (formal ...) expr ...))]))

[ Parent | on HN ]