Then there's the way I did it under the influence of macrophobia (I knew macros were valuable and important, but felt I didn't have time to learn them before the due date for the project at hand):
Define on-tick, on-draw, etc. as constructors for a variety of structs that each have a single field of type "function". Big-bang then became a variable-arity function that simply checked its arguments at run-time to see whether they were of any of those struct types. It didn't give quite as good error messages as the macro version, but it worked perfectly well and I could understand it without worrying about macros :-) Stephen Bloch [email protected] ____________________ Racket Users list: http://lists.racket-lang.org/users
