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Newsgroups: comp.lang.ada
Date: Wed, 21 Mar 2018 12:17:31 -0700 (PDT)
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Subject: Re: Ada-Oriented GUI
From: Shark8 <onewingedshark@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:51107
Date: 2018-03-21T12:17:31-07:00
List-Id: <comp.lang.ada>

On Wednesday, March 21, 2018 at 12:43:51 PM UTC-6, briot.e...@gmail.com wro=
te:
> I was also working on similar similar at the time (starting with promises=
 (https://github.com/briot/Ada-promises, though there's also a branch there=
 were I started to look at reactive programming).
>=20
> For me, the biggest obstacles were the need to instantiate a lot of gener=
ics, because the streams are associated with data, then get combined to cre=
ate other types of data, and so on. So we ended up with a soup of instantia=
tions (on the user side), which I had not quite managed to tame.

I had an idea about that, though even if I submit it now it wouldn't be put=
 in Ada 2020 -- but anyway, the idea was a sort of automatic instantiation.

Given

Generic
  Type Some_Type is private;
Procedure Generic_Swap( A, B : in out Some_Type );

you could say

Generic
  Type Element is private;
  Type Index is (<>);
  Type Array_Type is Array(Index range <>) of Element;
  USE Procedure Swap is new Generic_Swap( Element );
Procedure Generic_Sort( Input : in out Array_Type );

--...
Type Integer_Array is new Array(Integer range <>) of Integer;
Procedure Sort is new Generic_Sort( Integer, Integer, Integer_Array );

where the USE would instantiate Swap in Sort's instantiation; Swap itself c=
ould be reached via Sort.Swap and used in that manner, thereby cleaning up =
a lot of one-off instantiations.