Re: Generators/coroutines in future Ada?

["J-P. Rosen" <rosen@adalog.fr>]

Le 10/07/2017 à 15:38, Victor Porton a écrit :
> But AFAIK Ada does not support closures.
> 
> Are closures really needed to implement generators?
> 
> It is nearly impossible to add closures to Ada, right?

Taking the example from Wikipedia:

function startAt(x)
   function incrementBy(y)
       return x + y
   return incrementBy

variable closure1 = startAt(1)
variable closure2 = startAt(5)

This could be written as:
generic
   Start_Value : Integer
function Increment_By (X : integer) return Integer;

function Closure1 is new Increment_By (1);
function Closure2 is new Increment_By (5);

----
I can hear you saying that "generics are a poor man's workaround for the
lack of closure", to which I respond that closures are a limited
workaround for the lack of the more general concept of generic...

TBH, I don't think there is any value in the kind of discussion that
starts with "Language X is lacking feature A from language Y".

Express a problem in language Y, let people provide their solution in
language X, and then we can discuss the merits of each solution, given
some quality criteria. Note that sometimes, criteria can be at odds;
f.e., people nowadays value ease of writing and flexibility very much,
but these are quite opposed to safety, readability, and long term
maintenance which form the basic requirements of Ada.

-- 
J-P. Rosen
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