# [plt-scheme] is this a deep list ?

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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