[racket] Beginner problem

From: Stephen Bloch (johnelys at gmail.com)
Date: Sun Jun 9 07:10:25 EDT 2013

On Jun 8, 2013, at 10:26 PM, Steve Lett wrote:

> I am a beginner programmer and just came across Racket this week when I was on the Coursera website. I found the course called Intro to Systematic Program Design. I am trying to use Stephen Bloch's Picturing Programs. But my first attempt was using Quick-An Introduction to Racket with Pictures. Typing 5 I got 5. Typing "art gallery" I got "art gallery". But when I typed (circle 10) I got an error message "circle: this function is not defined".
> If I need a library there is a problem. My only internet conection is on the Android platform on a Galaxy Tab. So I have downloaded the DrRacket software and transferred it to my Windows Vista Laptop. I also have an XP desktop if I need it.
> So how can I get (circle 10) to work?
As others have already pointed out,

1) the "Quick" tutorial uses a slightly different language and library from the "Picturing Programs" book, which in turn uses a slightly different library from the "An Introduction to Systematic Program Design".  The latter two are mostly compatible with one another, and were designed for beginning programmers, so I would suggest you use them.

2) chapter 0.3 of the _Picturing Programs_ textbook explains how to choose languages and invoke the relevant library.

As others haven't already pointed out,

3) the libraries you need for "Quick", or "Picturing Programs", or "An Introduction to Systematic Program Design", are already downloaded in the same bundle that brought you DrRacket; you don't need a net connection after this.

4) the 2htdp/image library used in "An Introduction to Systematic Program Design" is a subset of the picturing-programs library used in _Picturing Programs_, so if you follow the directions in chapter 0.3 of the book, all the examples in both the book and the MOOC should work.

Dr. Stephen Bloch
Math/CS Dept, Adelphi University
sbloch at adelphi.edu

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