Hi Stefano,

Stefano Zacchiroli wrote:

>On Wed, Jun 04, 2003 at 05:13:27PM +0200, Christophe TROESTLER wrote:
>  
>
>>Given this, it rather seems that List.map is fine -- for if one really
>>wants speed, one will compile to native code and the bytecode version
>>    
>>
>
>My point is not having speed, but rather having tail recursion. In many
>cases lists are the correct data structure even for "a lot of elements".
>
>I've always thought that tail recursive version of map would have been
>terribly slower than not tail recrusive one due to the additional
>reversal. 
>
A year ago I 'benchmarked' almost exactly the alternatives you discuss 
within some real application. The difference was substantial, and I had 
to work with 'lots of elements'. List.rev took significant time, you 
can't neglect this. I even thought about implementing List.map as a C 
extension which calls the first argument as a callback and use pointer 
operations to build the list without consuming the stack. Not sure if 
it's a _proper-way-to-go_ :-).

Alexander


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