(Nils' Scheme Snippets)

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(flatten pair) => list

Purpose

Convert tree to flat list.

Arguments

tree	tree to flatten

Example

(flatten '(a (b ((c) d . e)))) => (a b c d e)

(define (flatten x)
  (letrec
    ((f (lambda (x r)
          (cond ((null? x) r)
                ((pair? x)
                  (f (car x)
                     (f (cdr x) r)))
                (else (cons x r))))))
    (f x '())))