[Caml-list] Is there a way to abort Stream.iter ?

[Caml-list] Is there a way to abort Stream.iter ?

[Jon Kleiser]

In my little program here <http://folk.uio.no/jkleiser/ocaml/read_vec.ml> I’m reading and processing a text file by doing this:

let process_lines lines =
  let start_time = Sys.time () in
  Stream.iter process_line lines;
  let finish_time = Sys.time () in
  Printf.printf "\nTime used: %f secs\n" (finish_time -. start_time)

. . . where the ‘lines’ input is coming from ‘(line_stream_of_channel in_channel)’.

Is there a way to abort the Stream.iter processing based on some condition detected by the ‘process_line’ function? Could it be done by throwing an exception? Maybe I should use something else than Stream.iter ?

/Jon

Re: [Caml-list] Is there a way to abort Stream.iter ?

[Yaron Minsky]

First of all, you should probably use a Pipe.t rather than a Stream.t.
Streams don't provide you with a way of pushing back, meaning the
process that's filling data into the Stream won't slow down if you're
slow in draining data from it. Pipes give you a mechanism for doing
this, in that a Pipe has a bounded amount of slack.

For pipes, when I want to control the exit time, I'll typically do a
recursive loop using Pipe.read or Pipe.read'. You can do something
similar with streams.

y

On Fri, May 12, 2017 at 10:34 AM, Jon Kleiser <jon.kleiser@ceres.no> wrote:
> In my little program here <http://folk.uio.no/jkleiser/ocaml/read_vec.ml> I’m reading and processing a text file by doing this:
>
> let process_lines lines =
>   let start_time = Sys.time () in
>   Stream.iter process_line lines;
>   let finish_time = Sys.time () in
>   Printf.printf "\nTime used: %f secs\n" (finish_time -. start_time)
>
> . . . where the ‘lines’ input is coming from ‘(line_stream_of_channel in_channel)’.
>
> Is there a way to abort the Stream.iter processing based on some condition detected by the ‘process_line’ function? Could it be done by throwing an exception? Maybe I should use something else than Stream.iter ?
>
> /Jon
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa.inria.fr/sympa/arc/caml-list
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs

Re: [Caml-list] Is there a way to abort Stream.iter ?

[Yaron Minsky]

Also, as you can see here:

https://github.com/janestreet/async_kernel/blob/master/src/pipe.mli#L525

Pipe.iter and Pipe.iter' will terminate if the callback throws.

y

On Sat, May 13, 2017 at 8:24 AM, Yaron Minsky <yminsky@janestreet.com> wrote:
> First of all, you should probably use a Pipe.t rather than a Stream.t.
> Streams don't provide you with a way of pushing back, meaning the
> process that's filling data into the Stream won't slow down if you're
> slow in draining data from it. Pipes give you a mechanism for doing
> this, in that a Pipe has a bounded amount of slack.
>
> For pipes, when I want to control the exit time, I'll typically do a
> recursive loop using Pipe.read or Pipe.read'. You can do something
> similar with streams.
>
> y
>
> On Fri, May 12, 2017 at 10:34 AM, Jon Kleiser <jon.kleiser@ceres.no> wrote:
>> In my little program here <http://folk.uio.no/jkleiser/ocaml/read_vec.ml> I’m reading and processing a text file by doing this:
>>
>> let process_lines lines =
>>   let start_time = Sys.time () in
>>   Stream.iter process_line lines;
>>   let finish_time = Sys.time () in
>>   Printf.printf "\nTime used: %f secs\n" (finish_time -. start_time)
>>
>> . . . where the ‘lines’ input is coming from ‘(line_stream_of_channel in_channel)’.
>>
>> Is there a way to abort the Stream.iter processing based on some condition detected by the ‘process_line’ function? Could it be done by throwing an exception? Maybe I should use something else than Stream.iter ?
>>
>> /Jon
>>
>> --
>> Caml-list mailing list.  Subscription management and archives:
>> https://sympa.inria.fr/sympa/arc/caml-list
>> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>> Bug reports: http://caml.inria.fr/bin/caml-bugs