> Probably the most distinctive feature of MDL is its mechanism for user-defined types, which is the best of any language with which we are familiar.
> User-defined types have been retrofitted on some of the newer versions of Lisp, but in most cases they can be used only with special functions and cannot be used in the same general way that Lists can.
Can you elaborate on this? The examples from the PFF suggest it's just the usual lispy type declarations.
> User-defined types have been retrofitted on some of the newer versions of Lisp, but in most cases they can be used only with special functions and cannot be used in the same general way that Lists can.
Can you elaborate on this? The examples from the PFF suggest it's just the usual lispy type declarations.