Range Fun in Ruby

example.rb

(-10..-5).include?(-7)
#=> true 
(-5..-10).include?(-7)
#=> false 
(10..5).include?(7)
#=> false 
(5..10).include?(7)
#=> true 

# OK, so maybe 10..5 wraps the whole set of integers?

(10..5).include?(3)
#=> false 
(10..5).include?(11)
#=> false 

# Nope...

range_code_extract.c

// This shows why this is so :trollface:
range_cover(VALUE range, VALUE val)
{
    VALUE beg, end;

    beg = RANGE_BEG(range);
    end = RANGE_END(range);
    if (r_le(beg, val)) {
        if (EXCL(range)) {
            if (r_lt(val, end))
                return Qtrue;
        }
        else {
            if (r_le(val, end))
                return Qtrue;
        }
    }
    return Qfalse;
}