Re: [q-lang-users] Symbol type

[Albert G. <Dr....@t-...>]

Burton Samograd wrote:
> Is the Symbol type left out for a reason, or
> is it under a different name that I haven't found yet?  Would there be
> any objection to adding it?

Yes, in fact it would be fairly useful to have a Symbol type (and 
subtypes FunSymbol and VarSymbol) for doing meta-programming, but that 
interferes with Q's current type system which only has single 
inheritance. Hence a constant symbol couldn't be a member of its own 
(user-defined) type, which might have its own supertype, and the Symbol 
type at the same time. So, until Q gets multiple inheritance, you'll 
just have to put up with the issym function and friends.

We've actually discussed the issue of multiple inheritance here a while 
ago and, looking at the code, I found that extending the construction 
algorithm for the pattern matching automaton to handle multiple 
supertypes is not straightforward. So I'm postponing this until I have a 
bytecode compiler written in Q itself (that's one of the reasons I'm 
working on Q Yacc and Lex), this will make it much easier to implement 
such changes.

Cheers,
Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag