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Re: Comprehension with two variables - explanation needed

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Date Mon, 24 Nov 2014 16:42:06 -0800
Subject Re: Comprehension with two variables - explanation needed
From Dan Stromberg <drsalists@gmail.com>
To "Steven D'Aprano" <steve@pearwood.info>
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On Sun, Nov 23, 2014 at 8:42 PM, Steven D'Aprano <steve@pearwood.info> wrote:
> On Sun, 23 Nov 2014 08:45:39 -0800, Rustom Mody wrote:
>> First a one-line solution in haskell
>>
>> sieve (p:xs)   =    p:sieve [x | x <- xs, x `mod` p /= 0]
>
> Don't use that! That is a horribly inefficient way to generate primes.
>
> Mathematically, it is a version of Euler's Sieve. It is sometimes wrongly
> described as "Sieve of Eratosthenes", but that is wrong. Due to it's
> horrible performance, Melissa O'Neill calls this the "Sleight on
> Eratosthenes":

I don't read Haskell, but here's a Sieve (or at least I thought it was
a Sieve) and a few other prime-related things:
http://stromberg.dnsalias.org/~dstromberg/primes/

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Thread

Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 16:56 +0200
  Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 07:09 -0800
    RE: Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 17:37 +0200
    Re: Comprehension with two variables - explanation needed Chris Angelico <rosuav@gmail.com> - 2014-11-24 02:42 +1100
    RE: Comprehension with two variables - explanation needed Skip Montanaro <skip.montanaro@gmail.com> - 2014-11-23 09:45 -0600
      Re: Comprehension with two variables - explanation needed Roy Smith <roy@panix.com> - 2014-11-23 10:57 -0500
        Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 08:45 -0800
          Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 09:17 -0800
          RE: Comprehension with two variables - explanation needed "Ivan Evstegneev" <webmailgroups@gmail.com> - 2014-11-23 19:27 +0200
          Re: Comprehension with two variables - explanation needed Steven D'Aprano <steve@pearwood.info> - 2014-11-24 04:42 +0000
            Re: Comprehension with two variables - explanation needed Chris Angelico <rosuav@gmail.com> - 2014-11-24 15:51 +1100
              Re: Comprehension with two variables - explanation needed Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-11-25 09:20 +1100
            Re: Comprehension with two variables - explanation needed Rustom Mody <rustompmody@gmail.com> - 2014-11-23 22:47 -0800
            Re: Comprehension with two variables - explanation needed Dan Stromberg <drsalists@gmail.com> - 2014-11-24 16:42 -0800
        Re: Comprehension with two variables - explanation needed Skip Montanaro <skip.montanaro@gmail.com> - 2014-11-23 10:45 -0600
        Re: Comprehension with two variables - explanation needed Roy Smith <roy@panix.com> - 2014-11-23 12:08 -0500
        Re: Comprehension with two variables - explanation needed Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2014-11-23 17:46 +0000

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