Programming language shootout: binary trees

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This is a Gambit implementation of the binary trees benchmark of the Computer Language Benchmarks Game.

The program

#!gsi-script
;; The Computer Language Benchmarks Game
;; http://shootout.alioth.debian.org/
;;
;; Derived by Bradley Lucier from the Ikarus variant, which was
;; Derived by Michael D. Adams from the MzScheme variant, which was
;; Derived from the Chicken variant by Sven Hartrumpf

(declare (standard-bindings)(extended-bindings)(not safe)(fixnum))

(define-structure node left val right)
(define-structure leaf val)

(define (make item d)
  (if (= d 0)
      (make-leaf item)
      (let ((item2 (* item 2))
            (d2 (- d 1)))
        (make-node (make (- item2 1) d2) item (make item2 d2)))))

(define (check t)
  (if (leaf? t)
      (leaf-val t)
      (+ (node-val t) (- (check (node-left t)) (check (node-right t))))))

(define (main . argv)
  (let* ((min-depth 4)
         (max-depth (max (+ min-depth 2) (string->number (car argv)))))
    (let ((stretch-depth (+ max-depth 1)))
      (display "stretch tree of depth ")
      (display stretch-depth)
      (display "\t check: ")
      (display (check (make 0 stretch-depth)))
      (display "\n"))
    (let ((long-lived-tree (make 0 max-depth)))
      (do ((d 4 (+ d 2)))
          ((> d max-depth))
        (let ((iterations
               (fxarithmetic-shift-left 1 (+ (- max-depth d) min-depth))))
          (do ((i 0 (+ i 1))
	       (c 0 (+ c (check (make i d)) (check (make (- i) d)))))
	      ((>= i iterations)
	       (display (* 2 iterations))
	       (display "\t trees of depth ")
	       (display d)
	       (display "\t check: ")
	       (display c)
	       (display "\n")))))
      (display "long lived tree of depth ")
      (display max-depth)
      (display "\t check: ")
      (display (check long-lived-tree))
      (display "\n"))))

Compiling

gsc binary-trees

Running

gsi binary-trees n
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