optimization of list comprehensions

Thomas Johnsson <>
Fri Mar 10 14:05:36 CET 2006


Sorry for the noise, the link I meant to include was, more specifically
http://csg.lcs.mit.edu/pubs/memos/Memo-284/memo-284-2.pdf
--Thomas

Thomas Johnsson wrote:

> Hm yes, "small is beautiful" is true perhaps more often than one might 
> think....
> perhaps a useful middle of the road approach would be to provide 
> efficient looping implementation of the following pattern
>    lists:foldl(fun(..pat...)-> ... expr.. end, Z, [ list 
> comprehension....] )
> and also point that out in the documentation.
>
> As an example of "the whole shebang", ie a (purely!) functional 
> language that has a loop construct, c.f. Id, see
> http://csg.csail.mit.edu/pubs/publications.html ,
> later included in pH (parallel Haskell).
>
> Accumulating array comprehensions, anyone?
> -- Thomas
>
>
>
> Mats Cronqvist wrote:
>
>>
>>
>> Richard A. O'Keefe wrote:
>>
>>> [...]   If funs are not used when they are *appropriate*, then it isn't
>>> "perfectly fine" Erlang.
>>
>>
>>
>>   appropriateness is in the eye of the beholder.
>>
>>> [...]
>>> Remember, language features don't come free.
>>> *Someone* has to design them.
>>> *Someone* has to implement them.
>>> *Someone* has to document them.
>>> *Someone* has to revised training materials.
>>> This is more effort than you might think, so it had better have a
>>> high enough payoff.  If it is you doing all these things, then it's
>>> entirely up to your judgement whether to do it.  If you are asking
>>> other people to do them for you, you had better give them good reasons.
>>
>>
>>
>>   i'm well aware that new features don't come free. as a matter of 
>> fact, i could find out exactly how much it would cost.
>>   if i was certain that new notation would improve our product, i 
>> would be having this discussion directly with OTP. as it is, i'm a 
>> bit discouraged after noticing how little use of list comprehensions 
>> there actually is.
>>
>>   mats
>>
>
>





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