Primes

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Sieve of Eratosthenese by parallel (||) processes.

let rec
 from = lambda n. fromchan!n -> from (n+1),

 fromchan = chan,

 sieve = lambda inch.
   inch?p -> output!p {must be prime} ->
   let rec
     filter = inch?x ->
       if (x/p)*p<>x then {not p|x} connect!x -> filter
                     else filter,

     connect = chan

   in (filter || sieve connect)


in  from 2 || sieve fromchan

{\fB Parallel Sieve of Eratosthenese. \fP}
example c1993.

A process is set up for each new prime -- to remove duplicates of that prime.


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pfl...
|   choice
|| parallel
-> sequence
? input act
! output act
chan new channel

© L. Allison   http://www.allisons.org/ll/   (or as otherwise indicated),
Faculty of Information Technology (Clayton), Monash University, Australia 3800 (6/'05 was School of Computer Science and Software Engineering, Fac. Info. Tech., Monash University,
was Department of Computer Science, Fac. Comp. & Info. Tech., '89 was Department of Computer Science, Fac. Sci., '68-'71 was Department of Information Science, Fac. Sci.)
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