Microsoft Patents 'IsNot'

[Terry Reedy]

""Martin v. Löwis"" <martin at v.loewis.de> wrote in message 
news:419fc77d$0$198$9b622d9e at news.freenet.de...

> To a reader, but not in an implementation. I believe that Microsoft
> would have allowed "foo is not Nothing" if they knew how to implement
> it.

I believe, having read the entire mess, that 'foo Is Not Nothing' is 
currently meaningful in MS Basic with the meaning 'foo Is (Not Nothing)', 
as I suggested one might naively parse Python.  Hence, changing the meaning 
to make (Is Not) a unit, as in Python, would break code.  But someone with 
access to one or more versions of current MS Basic would have to verify 
either way.

Of course, they *could* have learned to implement Is Not by reading the 
Python source ;-)  But IsNot is certainly much easier.  To my mind, their 
problem is not having thought through the matter carefully enough when they 
introduced Is.  I appreciate that Guido appears to have done much better 15 
years ago.

Terry J. Reedy