[erlang-questions] Lists Comprehentions vs. Accumulators

David Mercer <>
Tue Aug 21 22:55:48 CEST 2007


My guess is that it has to do with the fact that the list comprehension
version, odds_and_evens/1 allocates memory for the lists L, Odds, and Evens
simultaneously, whereas the accumulator version, odds_and_evens_acc/1 only
has to allocate enough memory for Odds, Evens, and only the suffix of L that
has not yet been processed.

 

Just a guess.

 

Cheers,

 

David

 

  _____  

From: 
[mailto:] On Behalf Of Shimon Cohen
Sent: Tuesday, August 21, 2007 15:15
To: 
Subject: [erlang-questions] Lists Comprehentions vs. Accumulators

 

Hi

My question concerning section 3.12 in Joe's "Programming Erlang":

Why odd_and_evens should be less space efficient than odd_and_evens_acc ?

I guess it must be somthing with tail-recursion, but can't see why 
List Comprehetions can't be implemented tail-recursive or even as a plain
loop.

Thanks,
Shimon Cohen.

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