On Wed, Dec 22, 2010 at 2:04 AM, Stephen Bloch <[email protected]> wrote:
> > On Dec 21, 2010, at 6:50 AM, Sayth Renshaw wrote: > > > Doing the netpay of employee tax = 0.15 and pay = hrs *12. From the > beginner tutorial. I see two ways a simple and a hard way but neither work. > > > > Hard way > > > > (define (hours h) > > (h : number?)) > > (define (tax t) > > (= t 0.15)) > > (define (payrate p) > > (= p $12.00)) > > (define (netpay hours tax payrate) > > (* h p)-(* t(* h p))) > > Something else I forgot to mention in my previous message: you're quite > right to want to give names to the tax rate and the hourly pay. The usual > way to do this in Beginner Racket would be > (define tax-rate 0.15) > (define pay-rate 12) > Note that these definitions are OUTSIDE the definition of "netpay". > > You can then use these in functions you define. For example, the > "inventory" step of this function definition would become > (define (netpay hours) > ; hours a number > ; pay-rate a number ($/hour) > ; tax-rate a number > ... > ) > and then the body could use all three of these variable names. > > Later in the book, you'll learn another way to do it, using "local > variables" so the names "tax-rate" and "pay-rate" are visible only INSIDE > "netpay": > (define (netpay hours) > (local [(define tax-rate 0.15) > (define pay-rate 12)] > ; hours a number > ; tax-rate a number > ; pay-rate a number ($/hour) > ... > )) > This version doesn't work in Beginning Student Language, though; you need > Intermediate Student Language. > > > > > Stephen Bloch > [email protected] > > Firstly thank you very much for the feedback and ideas its very appreciated. I am following the book again and your examples but i am rewriting examples so I am learning it. I came to this as a solution based on feeedback but it is erroring on the word gross as part of my netpay function. Do i need to define the gross function in my netpay function? (define tax-rate 0.15) (define pay-rate 12) (define (gross hours) (* hours pay-rate)) (define (netpay gross tax-rate) (gross (- tax-rate))) Not quite grabbing something intrinsic, unfortunately Norman this is the start of the book..If I have defined gross function as suggested earlier why can't my netpay function use it?
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