Ah, I see. But in the case of the bitwise operators it just changes the result type from unsigned to signed. 

'''
Used on numbers, the bitwise operators ("&", "|", "^", "~", "<<", and ">>") always produce integral results. (But see also Bitwise String Operators.) However, use integer still has meaning for them. By default, their results are interpreted as unsigned integers, but if use integer is in effect, their results are interpreted as signed integers.
'''

My calculator app, for instance, gives me the unsigned result for 'not 1' .. So both results are actually correct, it's just a matter of interpretation.