Re: pmc_type

Stéphane Payrard writes:
> That would allow to implement typechecking in imcc.
> 
>   .sym Scalar a
>   a = new .PerlInt  # ok.  Perlint is derived from Scalar

Ugh, yeah, but what does that buy you?  In dynamic languages pure
derivational typechecking is very close to useless.  The reason C++[1]
has pure derivational semantics is because of implementation.  The
vtable functions have the same relative address, so you can use a
derived object interchangably.  In a language where methods are looked
up by name, such strictures are more often over-restrictive than
helpful.

Anyway, that's just my rant.  If such a thing is to be in imcc, it
_must_ be optional without loss of feature.  I have quibble with the
automatic typechecking of .param variables for the same reason.

Luke

[1] And the reason Java has it is because C++ did.  Great design work,
guys.