Mutually recursive and "out of order" type declarations

[thomasmcoffee]

Mutually recursive type declarations such as

type A
        a :: B
        b
end

type B
        c :: A
        d
end

appear to be presently unsupported, as per this discussion:

https://groups.google.com/forum/#!msg/julia-users/LctRzct1R-M/s_vLVUxSyVcJ

More generally, "out of order" type declarations also appear to be unsupported.

Mutually recursive declarations are important for many recursive data structures: in complex cases, the workarounds required to produce singly recursive declarations can produce highly unreadable code with excessive redundancy and obscure relationships to the original concept.

"Out of order" declarations are important for some forms of generic programming that depend on altering a subset of type definitions: in complex cases, the workarounds required to organize the inclusions in ordered form defeat much of the purpose of avoiding the unnecessary code duplication.

I believe this issue is already well known, but I did not find an open issue on Github, which prevents easily checking its status.

[simonster]

I think the existing issue is #269.

[StefanKarpinski]

Yep. It's an old one. Closing as dup.

[thomasmcoffee]

Thanks --- didn't find it using the keyword "recursive."