memoize-test.scm

gosh> (define (memoize fn)
	(let ((cache (make-hash-table 'equal?)))
	  (lambda args
	    (let ((val (hash-table-get cache args #f)))
	      (if val val
		  (hash-table-put! cache args (apply fn args)))))))
memoize
gosh> (define (fib n)
	(if (< n 2)
	    1
	    (+ (fib (- n 1))(fib (- n 2)))))
fib
gosh> (time (fib 35))
;(time (fib 35))
; real   2.451
; user   2.450
; sys    0.000
14930352
gosh> (time ((memoize fib) 35))
;(time ((memoize fib) 35))
; real   2.580
; user   2.570
; sys    0.000
#<undef>
gosh> (time ((memoize fib) 35))
;(time ((memoize fib) 35))
; real   2.438
; user   2.430
; sys    0.000
#<undef>
gosh> 

right-way-of-using-memoize.scm

gosh> (define slowid (memoize fib))
slowid
gosh> (time (slowid 35))
;(time (slowid 35))
; real   2.549
; user   2.510
; sys    0.000
#<undef>
gosh> (time (slowid 35))
;(time (slowid 35))
; real   0.000
; user   0.000
; sys    0.000
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gosh>