Quiz! Was: Re: New functions: input() and reverse() -Reply
>>> "Carl R. White" <C.R.White at SCM.BRAD.AC.UK> 10/20/98 07:50am
>>>
i) Give the semantic difference between the following two subroutines.
One is self-referential (?) not sure what you want here...
ii) Give the contents of X and Y at the end of the program.
X: {4,6,2,6,{3,2,{3,8},4},9,7,9,{1,5,9,2,{6,5},3,5,8},4,1,3}
Y: {4,6,2,6,4,8,3,2,3,9,7,9,8,5,3,5,6,2,9,5,1,4,1,3}
(excuse any typos)
iii) Which function is more correct? (In your opinion) Discuss.
[I hate "Discuss" questions >:^> ]
This reminds me of one of Hofstadter's essays in GEB. Given that we
tend to think (aside from Eu's data structures) of a sequence as a list
of single depth (i.e. not containing other sequences), I feel that
intuitively, the first subroutine is more "correct". This subroutine simply
reverses the order of items in a list, without regards to the type of item it
is. The second however, as it recursively descends into its argument,
effectively reverses everything. I can imagine the sequence
{"one","two","three"} being turned into {"eerht","owt","eno"} using an
algorithm of this sort - Not (at least to me) what someone would want if
calling reverse on that sequence...
Additionally, the recursive function flattens the sequence, which I
assume is NOT what you were originally intending 
iv) BONUS question. Where have I got the "Start" numbers from? :)
pi
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