[vhantz]

> Stanza provides an optional type system, garbage collection, and a multimethod based object system. But if you don't like Stanza's object system, there is no way to write your own. This is one of the main directions of programming language research. Can we design a language so expressive that library writers can easily write the most appropriate object system, or most appropriate type system, to fit their application? Perhaps one day we'll have such a language.

We already have it. It's an obscure little language called C++. Tise interested in those kinds of extensions to a language should look into Herb Sutter's experiments with cppfront: https://hsutter.github.io/cppfront/welcome/overview/

[lelanthran]

C++ is most definitely not it.

Lisp is what you are after if you want to include some object system as a library, or a new type of switch statement as a library or a new kind of if statement as a library.

C++ can do none of that.

[AnimalMuppet]

C++ can do some of that. Let's say I want an if statement that takes an integer and three blocks of code. It executes the first block if the integer is less than zero, the second if it is zero, and the third if it is positive.

OK, if you squint enough that by "block of code" you mean closure, or function object, then I can write that in C++. I can make the if statement a free-standing function (that is, not a member of a class), and add it to any library I wish.

Now, you can say that it's going to be tedious to use that, because you have to set up three closures every time you want to call this "super if". And you'd be right, but that's a different argument.

[pjmlp]

C++26 reflection alongside compile time code execution, and template metaprogramming, can already do a lot.

It is the best way? Probably not, but we seldom get to chose what mainstream languages win out on the field.