Re: Fun: the Ada assignment operator is an alias of the equivalence operator

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Sat, 28 May 2011 02:48:29 +0200, Yannick Duchêne (Hibou57) wrote:

> A very light topic: I've just discovered the Ada / Pascal assignment  
> operator, is one of the alias of the logical-equivalence or defined-as  
> operator, that is, “ := ” is an alias of “ ≡ ”.

I didn't see that usage of ":=" ("Defined-as" is not same "equivalent").

For "defined-as" I saw "=" with a small triangle or word "def" under it. In
grammar definitions "::=" or "->".

≡ is indeed used as equivalent/tautological.

> This is a rather good choice which was made… would have been a perfect  
> choice is this was not used for side effects (let say this is just the  
> interpretation context which slightly vary :-D ).

Assignment is not a logical operation, variables are not logical
predicates. Even

   A := B;
   Post (A = B); -- Not necessarily true.

(A variable is a mapping of the program state onto the domain values set.
Assignment merely denotes a state transition.)

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de