Arc Forumnew | comments | leaders | submitlogin
3 points by rocketnia 268 days ago | link | parent

Isn't Common Lisp a language with a package system and unhygienic macros?

Common Lisp's approach is that the way a symbol is read incorporates information about the current namespace. That way usually all symbols, even quoted ones, can only have collisions if they have collisions within the same file, and this makes hygiene problems easier to debug on a per-file basis.

I don't think it's my favorite approach, but it could very well be a viable approach for Arc. I was using an approach somewhat like this in Lathe's namespace system, although instead of qualifying symbols at read time, I was qualifying each of them individually as needed, using Arc macros.



2 points by rocketnia 268 days ago | link

Oh right, Clojure has unhygienic macros too. Clojure symbols also have namespaces as in Common Lisp.

-----

3 points by krapp 268 days ago | link

I guess the problem isn't the unhygienic macros, per se, but unhygienic macros and lack of namespaces.

Do you think it would be possible to get ns.arc to work with macros and feasible to add it to the core language?

-----

2 points by rocketnia 267 days ago | link

Good question, but ns.arc manipulates what Racket calls namespaces, which are data structures that carry certain state and variable bindings we might usually think of as "global," particularly the definitions of top-level variables.

What Common Lisp and Clojure call namespaces are like prefixes that get prepended to every symbol in a file, changing them from unqualified names into qualified names.

I think namespaces are a fine approach for Arc. If Anarki's going to have both, it's probably best to rename Anarki's interactions with Racket namespaces (like in ns.arc) so they're called "environments" or something, to reduce confusion. I think they will essentially fit the role of what Common Lisp calls environments.

Of course, people doing Racket interop will still need to know they're called namespaces on the Racket side. Is there another name we can use for Common Lisp style namespaces? "Qualifications" seems like it could work.

-----

3 points by i4cu 267 days ago | link

> Is there another name we can use for Common Lisp style namespaces?

realms ?

going for brevity here :)

-----