~/NetBeansProjects/rubinius ➔ ruby -r shotgun/lib/primitives.rb -r shotgun/lib/jprimitives.rb -e "ShotgunPrimitives.new.generate_select(STDOUT)"
## RubiniusPrimitives.java
public static IRubyObject cpu_primitive_add(ThreadContext context, IRubyObject self, IRubyObject[] args, Block block) {
    ARITY(1);
    GUARD(FIXNUM_P(msg->recv));
    OBJECT t1 = stack_pop();
    if(FIXNUM_P(t1)) {
      RET(fixnum_add(state, msg->recv, t1));
    } else if(BIGNUM_P(t1)) {
      RET(bignum_add(state, bignum_new(state, N2I(msg->recv)), t1));
    } else if(FLOAT_P(t1)) {
      OBJECT t2 = float_coerce(state, msg->recv);
      RET(float_new(state, FLOAT_TO_DOUBLE(t2) + FLOAT_TO_DOUBLE(t1)));
    } else {
      FAIL();
    }
}
public static IRubyObject cpu_primitive_bignum_add(ThreadContext context, IRubyObject self, IRubyObject[] args, Block block) {
    ARITY(1);
    GUARD(BIGNUM_P(msg->recv));
    OBJECT t1 = stack_pop();
    if(BIGNUM_P(t1) || FIXNUM_P(t1)) {
      RET(bignum_add(state, msg->recv, t1));
    } else if(FLOAT_P(t1)) {
      double a = bignum_to_double(state, msg->recv);
      RET(float_new(state, a + FLOAT_TO_DOUBLE(t1)));
    } else {
      FAIL();
    }
}
public static IRubyObject cpu_primitive_sub(ThreadContext context, IRubyObject self, IRubyObject[] args, Block block) {
    ARITY(1);
    GUARD(FIXNUM_P(msg->recv));
    OBJECT t1 = stack_pop();
    if(FIXNUM_P(t1)) {
      RET(fixnum_sub(state, msg->recv, t1));
    } else if(BIGNUM_P(t1)) {
      RET(bignum_sub(state, bignum_new(state, N2I(msg->recv)), t1));
    } else if(FLOAT_P(t1)) {
      OBJECT t2 = float_coerce(state, msg->recv);
      RET(float_new(state, FLOAT_TO_DOUBLE(t2) - FLOAT_TO_DOUBLE(t1)));
    } else {
      FAIL();
...