Re: Strings with discriminated records

["Randy Brukardt" <randy@rrsoftware.com>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:peljsm$q5i$1@gioia.aioe.org...
> On 2018-05-30 12:31 AM, Randy Brukardt wrote:
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
>> news:peegke$rt1$1@gioia.aioe.org...
>> ...
>>> as a poor-man solution to supertyping. I.e. if it were possible to make
>>> Message a subtype of String (by providing conversions), you could simply
>>> write:
>>>
>>>     M : Message := "Hello World";
>>
>> Or you could just give string literals to type Message (although you'll 
>> have
>> to wait a bit for that capability -- but it should be in Ada 2020 -
>> finally).
>
> Yes, I heard about use-defined literals, I am glad they made into Ada.
>
> However subtyping per conversions is a more general approach which would 
> work for literals too as it does with universal types.

Yes, but it's never gotten any traction. I've never been able to get any 
interest in any sort of user-defined conversion - there is a large faction 
that thinks function calls are good enough for that.

                              Randy.