Re: [Jscheme-user] linj Lisp to Java compiler

[Geoffrey K. <ge...@kn...>]

If there is an orderly way to write code in a CLOS style and use LINJ 
to generate Java classes and interfaces, and if aspects can be weaved 
into the Java compilation, this might even convince PHBs.

Geoffrey
--
Geoffrey S. Knauth | http://knauth.org/gsk

On Friday, October 17, 2003, at 11:16 AM, Ken Anderson wrote:

> Bottom Secret (Don't tell managment)
>
> At the International Lisp Conference, 
> http://www.international-lisp-conference.org/
> there was a nice presentation about Linj a Lisp to Java compiler.  The 
> code is not available yet, but there is a nice tutorial: 
> http://www.evaluator.pt/downloads/tutorial.html
>
> One of the goals is to make human readable Java code, so your clients 
> can't tell that you're not programming in Java (though some suspect 
> that something strange is going on). So, for example, this Common Lisp 
> code:
>
> (defun fact (n)
>   (if (= n 0)
>      1
>      (* n (fact (1- n)))))
>
> (defun main ()
>   (dotimes (i 6)
>     (let ((n (* i 10)))
>       (format t "(fact ~A) -> ~A~%" n (fact n)))))
> compiles to this Java code:
> import linj.Bignum;
> public class Factorial extends Object {
>     public static Bignum fact(Bignum n) {
>         if (n.compareTo(Bignum.valueOf(0)) == 0) {
>             return Bignum.valueOf(1);
>         } else {
>             return n.multiply(fact(n.subtract(Bignum.valueOf(1))));
>         }
>     }
>
>     public static void main(String[] outsideArgs) {
>         for (int i = 0; i < 6; ++i) {
>             int n = i * 10;
>             System.out.print("(fact ");
>             System.out.print(n);
>             System.out.print(") -> ");
>             System.out.println(fact(Bignum.valueOf(n)));
>         }
>     }
> }
>
> Notice the nice type inference!  You can add type declarations like 
> this:
>
> (defun fact (n/int)
>   (if (= n 0) 1L
>     (* n (fact (1- n)))))
>
> One of the real powers of this is that you can define a minilanguage 
> in Lisp macros and have Linj generate Java code for you!  You can even 
> put a comment in Java code that Linj will transform into Java code.
>
> I can even imagine writing the JScheme primitives in Linj and maybe 
> even a JScheme compiler and ...
>
> k