Array#intersect?

static VALUE
rb_ary_intersect_p(VALUE ary1, VALUE ary2)
{
    VALUE hash, v, result, shorter, longer;
    st_data_t vv;
    long i;

    ary2 = to_ary(ary2);
    if (RARRAY_LEN(ary1) == 0 || RARRAY_LEN(ary2) == 0) return Qfalse;

    if (RARRAY_LEN(ary1) <= SMALL_ARRAY_LEN && RARRAY_LEN(ary2) <= SMALL_ARRAY_LEN) {
        for (i=0; i<RARRAY_LEN(ary1); i++) {
            v = RARRAY_AREF(ary1, i);
            if (rb_ary_includes_by_eql(ary2, v)) return Qtrue;
        }
        return Qfalse;
    }

    shorter = ary1;
    longer = ary2;
    if (RARRAY_LEN(ary1) > RARRAY_LEN(ary2)) {
        longer = ary1;
        shorter = ary2;
    }

    hash = ary_make_hash(shorter);
    result = Qfalse;

    for (i=0; i<RARRAY_LEN(longer); i++) {
        v = RARRAY_AREF(longer, i);
        vv = (st_data_t)v;
        if (rb_hash_stlike_lookup(hash, vv, 0)) {
            result = Qtrue;
            break;
        }
    }

    return result;
}