List Parameters

[danbaron]

Below, there are four function definitions.

Function g takes 6 parameters.

Function h takes 3 parameters.

Function time-g takes 6 parameters, and times function g.

Function time-h takes 3 parameters, and times function h.


' code ---------------------------------------------------------------------------------------------------------------------

#lang racket

(define (g a b c d e f)
(+ (expt a b) (expt c d) (expt e f)))

(define (h a b c)
(expt a (expt b c)))

(define (time-g a b c d e f)
(let ((t1 (current-milliseconds)))
(let ((result (g a b c d e f)))
(let ((t2 (current-milliseconds)))
(let ((tt (/ (- t2 t1) 1000.0)))
tt)))))

(define (time-h a b c)
(let ((t1 (current-milliseconds)))
(let ((result (h a b c)))
(let ((t2 (current-milliseconds)))
(let ((tt (/ (- t2 t1) 1000.0)))
tt)))))

' REPL interactions --------------------------------------------------------------------------------------------------------

Welcome to DrRacket, version 5.1 [3m].
Language: racket.

> (time-g 34565 67656 37916 34854 377252 76301)
1.159

> (time-h 7 7 7)
1.162
>


Is there a way to have just one time function, that will work for both g and h?

Yes.

Instead of passing the individual parameters to the functions, you pass the functions lists which contain the parameters.

:idea:


' code ---------------------------------------------------------------------------------------------------------------------

#lang racket

(define (g l)
(define a (first l))
(define b (second l))
(define c (third l))
(define d (fourth l))
(define e (fifth l))
(define f (sixth l))
(+ (expt a b) (expt c d) (expt e f)))

(define (h l)
(define a (first l))
(define b (second l))
(define c (third l))
(expt a (expt b c)))

(define (time fn l)
(let ((t1 (current-milliseconds)))
(let ((result (fn l)))
(let ((t2 (current-milliseconds)))
(let ((tt (/ (- t2 t1) 1000.0)))
tt)))))

' REPL interactions --------------------------------------------------------------------------------------------------------

Welcome to DrRacket, version 5.1 [3m].
Language: racket.

> (time g (list 34565 67656 37916 34854 377252 76301))
0.965

> (time h (list 7 7 7))
1.209
>