This directory contains print routines for the structures defined in
the ast/ directory.

The global *print-structure* controls printing of objects in the
structure system.  Values are:
  haskell  -- Prints haskell format expressions from ast
  struct   -- Prints the raw structs (with circularity check)
  top      -- Prints top level only of the struct

The file defs.scm has the basic hooks to the printer mechanism.  The
idea is that when *print-structure* is 'haskell, the print function stored
in the type descriptor will get used.  If there isn't a print function,
or if *print-structure* is false, then the thing will print out in
some generic way that's good for debugging purposes.

The macro define-printer is used to associate a print function with a
structure type.  Since these can be defined on the fly, the print
dispatching routine has to look up the inheritance chain of type
descriptors looking for the first inherited type that has a printer.