[racket] first vs car ; last vs cdr ; empty? vs null?

So if code is using first/rest instead of car/cdr when I already know the
lists are proper, it could incur a significant performance penalty? After
all, memoization still needs a table lookup each time I do a first/rest.

(i.e. implementing datastructures in terms of lists should use car/cdr for
performance right? any benchmarks?)

On Friday, March 7, 2014, Sean Kanaley <skanaley at gmail.com> wrote:

> Pardon me, but going back a bit where the blog about switching to
> immutable lists was mentioned...I saw an interesting comment about
> immutability and eq?.  Have any mathematicians come up with an answer for
> the meaning of eq? on permanently distinct but equivalent and immutable
> objects, e.g. (eq? (cons 3 2) (cons 3 2))?  What about on immutable objects
> that have mutable internal state, e.g. memoizing functions?
> Naive-but-memoized (fib 1000) is not necessarily the same as (fib 1000),
> unless the answer doesn't depend on the number of universes that have
> bigbanged meanwhile.
>
>
>
> On Fri, Mar 7, 2014 at 2:31 PM, Daniel Carrera <dcarrera at gmail.com<javascript:_e(%7B%7D,'cvml','dcarrera at gmail.com');>
> > wrote:
>
>> Thanks.
>>
>>
>> On 7 March 2014 20:22, Harry Spier <vasishtha.spier at gmail.com<javascript:_e(%7B%7D,'cvml','vasishtha.spier at gmail.com');>
>> > wrote:
>>
>>> See also this previous thread on the Racket list.
>>>  http://www.mail-archive.com/users%40racket-lang.org/msg12161.html
>>>
>>>
>>>
>>>
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>>
>>
>> --
>> When an engineer says that something can't be done, it's a code phrase
>> that means it's not fun to do.
>>
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>
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