Comment by curious9999_2

It was indeed the SPARK dialect I am referring to.

I find the Ada community difficult to navigate, the existence of multiple dialects does not make it easier. Please do correct me if I am wrong, and I apologize for any mistakes that I might have made.

If it is not the case that the SPARK language or its proprietary compiler is ahead of what is available publicly, why does this page say that pattern matching is in production:

https://github.com/AdaCore/ada-spark-rfcs/blob/master/featur...

While as far as I can tell, it is not part of normal, not-SPARK Ada, and either is not available in open source compilers, or might require enabling an extension?