Re: Writing a procedure in different style

[Taylan Kammer]

On 13.12.2020 08:06, Taylan Kammer wrote:
>    (define find-in-tree*
>       (λ (peg-tree filter-proc)
>
>         (define traverse
>           (λ (subtree rest)
>             (simple-format (current-output-port)
>                            "working with subtree ~a\n"
>                            subtree)
>             (cond
>              [(null? subtree)
>               (if (null? rest)
>                   '()
>                   (traverse (car rest) (cdr rest))]
>              [(pair? (first subtree))
>               (traverse (first subtree)
>                         (cons (cdr subtree) rest))]
>              [(filter-proc (first subtree))
>               (cons subtree
>                     (traverse (car rest) (cdr rest)))]
>              [else
>               (traverse (cdr subtree) rest)])))
>
>         (traverse peg-tree '())))

Correction, for third branch of the cond that didn't check if rest is null:

  (define find-in-tree*
     (λ (peg-tree filter-proc)

       (define traverse
         (λ (subtree rest)
           (simple-format (current-output-port)
                          "working with subtree ~a\n"
                          subtree)
           (cond
            [(null? subtree)
             (if (null? rest)
                 '()
                 (traverse (car rest) (cdr rest)))]
            [(pair? (first subtree))
             (traverse (first subtree)
                       (cons (cdr subtree) rest))]
            [(filter-proc (first subtree))
             (cons subtree
                   (if (null? rest)
                       '()
                       (traverse (car rest) (cdr rest))))]
            [else
             (traverse (cdr subtree) rest)])))

       (traverse peg-tree '())))


Taylan