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From: G. B. <nonlegitur@nmhp.invalid>
Newsgroups: comp.lang.ada
Subject: Re: stopping a loop iteration without exiting it
Date: Fri, 5 Jan 2018 19:09:08 -0000 (UTC)
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Robert A Duff <bobduff@TheWorld.com> wrote:
> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> I thought about really important cases, but could not invent syntax:
>> 
>> if X in T'Class then
>> declare
>> Same_X : T'Class renames T'Class (X);
> 
> That's something like pattern matching in languages
> like OCaml.

Swift adds convenience:

   if let Same_X = X as? T {
      ...
   }

“=“ goes with “let”; if the downcast fails, the
result is nil, and the condition becomes false.