One of the nice things about Racket is that it works a lot like algebra. You combine Racket expressions the same way you combine mathematical expressions. In math, you would write a single expression that's built out of smaller expressions, such as 10 * (x + 1). In Racket, you would write this as: (* 10 (+ x 1)). Just as in algebra, the innermost expressions are evaluated first, and the the results are used by the outer expressions to compute a final result. You will get farther in Racket by thinking in terms of evaluating expressions and reducing them to a result than by thinking in terms of executing a sequence of steps.
You may be interested in looking at some video lectures I made. The class got cancelled, so there are only a few lectures, but they deal with the basics of Racket expressions. They are at http://www.youtube.com/playlist?p=PL3F392F068BECB707 Justin On Wed, Jun 1, 2011 at 11:09 PM, Yingjian Ma <yingjian.ma1...@gmail.com> wrote: > Thank you both for your reply. > > My real need is to use the result of the first function in the second > function. Is there a standard way to pass a variable into the next > function? > > On Wed, Jun 1, 2011 at 6:24 PM, Shriram Krishnamurthi <s...@cs.brown.edu> > wrote: >> >> Also note that if you programmed in the Student Language levels, this >> function would be illegal (and it might give you some insight into how >> this programming style works). >> >> On Wed, Jun 1, 2011 at 9:19 PM, Justin Zamora <jus...@zamora.com> wrote: >> > On Wed, Jun 1, 2011 at 7:22 PM, Yingjian Ma <yingjian.ma1...@gmail.com> >> > wrote: >> >> >> >> In my question >> >> (define (p x) >> >> (+ x 10) >> >> (* x 10) >> >> ) >> >> It seems it only executes (* x 10) >> > >> > No, it executes both of them. It evaluates (+ x 10), then throws away >> > the value it just computed. Then it evaluated (* x 10), since that is >> > the last expression, the value gets returned as the value of the >> > function. When there is more than one expression in a function body, >> > all of them get evaluated, but only the last is returned. If you want >> > to use the results of both expressions, then you need to use two >> > functions, one for each expression, as Shriram said. >> > >> > Justin >> > >> > _________________________________________________ >> > For list-related administrative tasks: >> > http://lists.racket-lang.org/listinfo/users >> > > > > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
