[m-users.] Conjunction as an operator

[Julian Fondren]

On 2019-10-12 17:32, Volker Wysk wrote:
> Hi!
> 
> I need a conjunction of two terms, like this:
> 
>     X = (Str \= "" & Str \= ".")
> 

What is X supposed to be, here? What is its type? Whats a possible
value that it could have? If you want to fail if Str is either ""
or ".", you can do that with any of

   Str \= "", Str \= "."

   not (Str = "" ; Str = ".")

   ( if Str = "" ; Str = "." then fail else true )

A,B and A&B only differ operationally: A and B might be executed in
parallel in the second case.

> This doesn't work. I'm sure I don't understand what's going on. Could
> somebody please tell me how this is done?
> 
> Volker