[plt-scheme] is this a deep list ?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Sun Mar 30 22:34:56 EDT 2008

Precisely. The point of a data definition is to clarify how to  
generate the data that a function consumes (or produces). If you  
don't know that much, you can't design the function. -- Matthias

On Mar 30, 2008, at 2:59 PM, richard gere wrote:
> Since this is my first posting i want to first  thank the authors of
> htdp for such a wonderful book.
> I also want to confirm to you that i am not a "student" in any school
> or college.
>> From ex 11.2.4
> A deep-list is either
> 1. s where s is a symbol or
> 2. (cons dl empty) where dl is deep-list
> Now from 1 we can say 'doll is a deep-list
>> From 2 we can say (cons 'doll empty) is a deep list
>> From 2 we can say (cons (cons 'doll empty) empty ) is a deep list
> since it is in the form (cons dl empty)
> Now is this a deep list , (my understanding is that it is  not
> deep-list as per defination) :
> (cons  (cons 'doll (cons 'robot empty)) empty)
> why , well for it to be a deep-list the middle part has also to be  
> a deep-list .
> But middle part is in the form (cons 'doll dl)  i.e cons follwed by a
> symbol followed by a deep-list and as per defination
> there is no match , hence it is not a deep-list.
> Please confirm if my reasoning is correct for this deep-list as per
> defination given in the book
> Thank you
> veer
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