Re: Generators/coroutines in future Ada?

[Dennis Lee Bieber <wlfraed@ix.netcom.com>]

On Sun, 09 Jul 2017 23:19:23 +0300, Victor Porton <porton@narod.ru>
declaimed the following:

>Is it possible to implement generators and coroutines (like as in Python) in 
>a future version of Ada?
>
>I am not an expert on how generators are implemented. Is it possible in a 
>language like Ada?
>

	Generators -- not as you think of them (ad hoc, on-demand, creation).
cf:
http://www.adaic.org/resources/add_content/standards/05rm/html/RM-A-5-2.html
(which is focused on random number generation, but basically anything could
follow the schema). You'd have to define a (generic) package with a
generator type definition, and methods to manipulate state of the
generator. The instances of the generator type are what holds the state
between invocations.

>Well, I think it could add additional reliability, because programming of 
>processing of different "streams" becomes easier and thus less error prone.

	I wouldn't hold out much hope for coroutines. Ada was created from the
start with the concept of independent tasking (all the way back before
1980!). Formal co-routines (a la Modula-2) do not fit the philosophy as
they are a cooperative "task" switch (in classic co-routines, each routine
determines when it will transfer control to another, and possibly where in
that other transfer goes to -- it was even doable in FORTRAN-IV when
statement labels could be passed in/out of a call). I've never studied the
Python "co-routine" but it does not map to what I consider a co-routine.
-- 
	Wulfraed                 Dennis Lee Bieber         AF6VN
    wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/