Question

Long story:

I am doing a project for my functional programing class, and I thought of writing an AI controller in Lisp, for the Mario AI competition.

I was looking over frameworks/libraries/ways of calling Lisp code from Java, or even better Lisp-Java intercommunication.

I have looked at Jacol, but it is old, and it does not compile fine for me.

My best choice so far is: Jatha.
It is really neat, although some lisp constructs are not yet implemented, one can easily define his own constructs. For example mapcar and cond are not implemented.
I have implemented my own mapcar, named mapp in Lisp like this:

(defun map* (f l r) 
  (if (null l)
      r
      (map* f (rest l) (cons (funcall f (first l)) r))))

(defun mapp (f l)
    (reverse (map* f l nil)))

Now I have a simple function that uses this, for example, a function that numbers how many atoms there are in a non-linear list

(defun myfunc (l)
  (if (atom l)
      '1
      (apply '+ (mapp 'myfunc l)))) 

(myfunc '(6 2))

This all works fine in clisp
Now to call Lisp code from Java I used Jatha. All one has to do is import the Jatha library in the java project and load a lisp file like this (ex):

import org.jatha.*;
import org.jatha.dynatype.*;

public class Main {

    public static void main(String[] args) {
        Jatha lisp = new Jatha(false, false);
        lisp.init();
        lisp.start();
        LispValue file = lisp.makeString("X:\\lispproject\\test1.lisp");
        LispValue rez1 = lisp.load(file);
    }
}

While that code works fine in clisp, and other implementations, this code produces a StackOverflow


run:
APPLY: fn = +, args = ((1 1))
S: ((+ (QUOTE 1) (QUOTE 1)))
Exception in thread "main" java.lang.StackOverflowError
at java.lang.Long.toString(Long.java:242)
at java.lang.Long.toString(Long.java:100)
at java.lang.String.valueOf(String.java:2946)
at org.jatha.dynatype.StandardLispInteger.toString(StandardLispInteger.java:113)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:174)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:153)
at org.jatha.dynatype.StandardLispCons.toString(StandardLispCons.java:152)
at org.jatha.dynatype.StandardLispCons.toStringAsCdr_internal(StandardLispCons.java:17


So my question is, why does it do this? Is my code wrong?
Is it a bug in Jatha? See for yourself, it doesn’t take long to set up.
Have you ever done something similar?
Do you know any other better ways to do this? All I want is to call from Java some Lisp code, get it executed, and get back results computed by the Lisp code.
Thanks.

[Edit] Fixed code, pasted something wrong.

Answer 1

ABCL is a Common Lisp implementation that runs directly in the JVM – possibly it is the best option to run Common Lisp side by side with Java.