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[Caml-list] Generation of streams is slow
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Date: -- (:)
From: Daniel de Rauglaudre <daniel.de_rauglaudre@i...>
Subject: Re: [Caml-list] Generation of streams is slow
Hi,

On Fri, Jul 13, 2001 at 07:51:09PM -0700, Alexander V. Voinov wrote:

> Yes, the difference is substantial, but it gets longer and longer anyway
> with more elements parsed (for a slightly more complex program, which
> parses the stream as it is generated) and crashes at some point.

I did not test, but looking at your code, I see that neither parse_stream
nor parse_stream' is tail recursive! It is not a question of parsers, now:
your recurive calls are never the last action.

Perhaps this version would work (not tested):

  let rec parse_stream list s =
    match s with parser
      [< 'i; s' >] -> begin 
	if i mod 1000 = 0 then begin
	  printf "picked element %d\n" i; 
	  flush stdout
	end; 
	parse_stream (i :: list) s'
      end
    | [< >] -> (printf "end\n"; flush stdout; List.rev list)

  let _ = 
    print_list (parse_stream' [] (gen_stream 700000))

-- 
Daniel de RAUGLAUDRE
daniel.de_rauglaudre@inria.fr
http://cristal.inria.fr/~ddr/
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