LispForum

Firstly, you will need to quote the identifiers in your 'case' statement. I believe that your individual parsers (trec-if, trec-cond, trec-begin, ...) should be implemented something like the following: (define (trec-if fun expr term) (let ((consequent (cadr expr)) (alternative (caddr expr)) ) (if (...

Start with an empty dictionary (an alist ), and then traverse your input (using recursion); if you encounter an item that is not in your dictionary, add it with a count of "1". If the item you encounter is already in the dictionary, increment its count. When you reach the end of your input...

So i have 1 - (defparameter *s* (open animals)) Then i get kinda lost. 2 - (read *s*) ??? : : so far my file animals has "((Emu)(Dog Beaver))" The effect of reading an expression from a file is basically equivalent to what you would obtain by quoting the expression. (defparameter *s* '((E...

Why does first return NIL and rest return (NIL)? One can always be certain that there is only one first item in the list. Without knowing the length of the list, it is not possible to know how many items follow the first, so 'rest' returns them all as a list. Consider what (rest '(NIL NIL NIL)) eva...

If you don't mind reading a bit of C code then GNU's libavl documentation provides some of the most comprehensive coverage of binary trees I know of. It is written in a sort of "Donald Knuth documented code" style.

Even if unquoted empty lists were recognized, the following part of your expression is not a pair:

http://www.paulgraham.com/icad.html

While for this forum it is largely a matter of preaching to the choir, the sermon is nonetheless enjoyable.

(define (remove-duplicates lis) (cond ((null? lis) '() ) ((member (car lis) (cdr lis)) (remove-duplicates (cdr lis)) ) (else (cons (car lis) (remove-duplicates (cdr lis))) ))) (define-syntax quote-unique (syntax-rules () ((_ args ...) (remove-duplicates (quote (args ...))) ))) Perhaps?

Which dialect of Scheme are you running? (I don't know of any that use 'defun'.)

Also, you need to define all of your procedures push, pop, peek, show, and fb somewhere (so that they evaluate properly during invocation).

The following assumes that for (sub)lists to be considered similar to each other, they must have the same number of elements. (define (similar-struct? obj1 obj2) (cond ((and (atom? obj1) (atom? obj2)) #t ) ((atom? obj1) #f ) ((atom? obj2) #f) (else (and (similar-struct? (car obj1) (car obj2)) (simil...