[racket] HTDP exersise 12.4.2

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Sun Aug 28 17:59:55 EDT 2011

Cloud, sorry for the cryptic message but we promised our teachers not to publish solutions. Some of us make up some brand-new problems every semester we teach an HtDP course but most teachers don't have time. 

On Aug 28, 2011, at 5:08 PM, Stephen Bloch wrote:

> You've introduced numbers to a problem that doesn't involve numbers.  This usually indicates somebody who's still thinking in C or C++ and translating to Scheme/Racket rather than thinking "natively" in Scheme/Racket.

Of the criticisms that Stephen offered, the above is the most important one. Use the force, or in less archaic form: follow the  data definition in the organization of your program (the template). 

If you were to write down words on a page and explain the idea of inserting a letter everywhere, you would probably point a spaces between the letters to say "put this letter, here and here and there." (Index)Numbers are an artifact, especially of programming (and naive mathematics). 

Try again, if you're stuck, ask questions. Start questions with "I am following the design recipe and I am stuck on step 2 (or 3 4 5 6 7 8)." People know the problem and they will help 

-- Matthias

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