FASTRUBY!

Hello.java

public class Hello extends RObject {
    public Hello() {
        RObject __last = RNil;
    }

    public RObject hello_world() {
        RObject __last = RNil;
        __last = puts(new RFixnum(1)._plus_(new RFixnum(1)));
        __last = puts(new RString("Hello, world"));
        return __last;
    }

    public RObject fib(RObject a) {
        RObject __last = RNil;
        if (a._lt_(new RFixnum(2)).toBoolean()) {
            __last = a;
        } else {
            __last = fib(a._minus_(new RFixnum(1)))._plus_(fib(a._minus_(new RFixnum(2))));
        };
        return __last;
    }

}

hello.rb

class Hello
  def initialize

  end

  def hello_world
    puts 1 + 1
    puts "Hello, world"
  end

  def fib(a)
    if (a < 2)
      a
    else
      fib(a - 1) + fib(a - 2)
    end
  end
end

HelloRunner.java

public class HelloRunner {
  public static void main(String[] args) {
    new Hello().hello_world();
    for (int i = 0; i < 10; i++) {
      long start = System.currentTimeMillis();
      new Hello().fib(new RFixnum(35));
      System.out.println(System.currentTimeMillis() - start);
    }
  }
}

output.txt

system ~/projects/fastruby $ java HelloRunner
2
Hello, world
363
239
195
193
209
193
194
192
201
193

RBoolean.java

public class RBoolean extends RObject {
    public final boolean bool;
    public RBoolean(boolean bool) {
        this.bool = bool;
    }

    public RObject to_s() {
        return new RString(Boolean.toString(bool));
    }
}

RFixnum.java

public class RFixnum extends RObject {
    public final long fix;
    public RFixnum(long fix) {
        this.fix = fix;
    }

    public RObject to_s() {
        return new RString(Long.toString(fix));
    }

    public RObject to_int() {
        return this;
    }

    public RObject _plus_(RObject other) {
        return new RFixnum(fix + ((RFixnum)other.to_int()).fix);
    }

    public RObject _minus_(RObject other) {
        return new RFixnum(fix - ((RFixnum)other.to_int()).fix);
    }

    public RObject _lt_(RObject other) {
        return fix < ((RFixnum)other.to_int()).fix ? RTrue : RFalse;
    }
}

RKernel.java

public class RKernel {
    public static final RObject RNil = new RObject();
    public static final RObject RTrue = new RBoolean(true);
    public static final RObject RFalse = new RBoolean(false);

    public RObject puts(RObject... objects) {
        for (RObject object : objects) System.out.println(object);
        return RNil;
    }

    public RObject to_int() {
        throw new RuntimeException("can't convert to Integer: " + getClass().getName());
    }

    public RObject to_s() {
        return new RString("#<" + getClass().getName() + ">");
    }

    public String toString() {
        return to_s().toString();
    }

    public boolean toBoolean() {
        if (this == RNil || this == RFalse) return false;
        return true;
    }
}

RObject.java

public class RObject extends RKernel {
    public RObject Hello() {
        throw new RuntimeException("Hello");
    }
    public RObject hello_world() {
        throw new RuntimeException("hello_world");
    }
    public RObject _plus_(RObject arg0) {
        throw new RuntimeException("_plus_");
    }
    public RObject fib(RObject arg0) {
        throw new RuntimeException("fib");
    }
    public RObject _lt_(RObject arg0) {
        throw new RuntimeException("_lt_");
    }
    public RObject _minus_(RObject arg0) {
        throw new RuntimeException("_minus_");
    }
}

RString.java

public class RString extends RObject {
    private final String str;

    public RString(String str) {
        this.str = str;
    }

    public String toString() {
        return str;
    }
}