Append Example

First, remove all of the write functions from filter-code.ss. Then create the module append-capture.ss:

#lang scheme

(provide append |hello counter| |int hello counter| |inc hello counter|)

(define |hello counter| 0)

(define (|int hello counter|)
  (set! |hello counter| 0))

(define (|inc hello counter|)
  (set! |hello counter|
        (add1 |hello counter|)))

(define (append x y)
  (begin (set! |hello counter| (add1 |hello counter|))
         (cond
           [(empty? x) y]
           [else (cons (first x) (append (rest x) y))])))

Then in the options.ss file, you will need to include this module when you load the code:

(language scheme)
(loadcode assignfile.filt.ss)
(modules "append-capture.ss")

Now any test run with these options will increment the counter by n+1 every time append is called with a list of length n as its first argument.

-- SteveT - 22 Apr 2009