[plt-scheme] Struct Printer

Hello,

Jens Axel Søgaard <jensaxel at soegaard.net> writes:

> You could alter the current printer.

Yeah, that's what I'm doing now:

        http://www.theworld.com/~proteus/print-dispatch.scm

This is fast because the print-dispatch function extracts the
struct-type from a given object and does a lookup in the 'eq?' based
hash table.

Unfortunately, the ability to get the struct-type requires a
sufficiently senior inspector and I'd like this to also work with
opaque structs. I have another version with a table that is an alist
mapping predicates to printers. Of course, this is slow because the
print-dispatch function may have to search the whole list for a
matching predicate...

I really wish Scheme had a type-of function.

Some days Common Lisp looks very pretty. :-/

Ed