Qua, 2008-04-30 às 15:55 +0200, TSa escreveu: > But the type system is part of the language core. > As such 'isa' and 'like' or assignment and binding semantics > need a definition.
Actually, this is one of the hardest parts of implementing Perl 6, because even 'isa', 'like', assignment and binding are dependent on the representation of the given objects, so even such basic operations are polymorphic. This makes the bootstrap of the type system harder, but not impossible. What happens is that, as it is polymorphic, I can provide known low-level implementation of higher-level types that will interoperate transparently with them. By doing that I can bootstrap by special-casing the low-level implementations and getting out of the water that way. This also allows some other interesting features, like the fact that I may have a constant identifier that interoperates with Str while I still can compare to of them simply by comparing their pointer addresses, or by providing a shadow object that points to the inner data structure of other object in order to expose the expected API. In fact, that is the exact point that makes it possible for Perl 6 to have a *fully* boostrapped type system. What defines native types in Perl 6 is not that they have a incompatible lowlevel structure (because they don't, unless optimized), but that they are the only types that the interpreter may expect to know how they look like. Everything else should be opaque to the interpreter (but eventually the optimizer may have a catalog to inspect the internals directly). Take a look at http://www.perlfoundation.org/perl6/index.cgi?smop_p6opaque_implementation and at http://www.perlfoundation.org/perl6/index.cgi?smop_oo_api To see how that's being implemented in SMOP. daniel
