Re: Perl 6 sorting (was: Re: Sort: By keys, values, and their returning values.)

Having Pair objects and a built-in Schwartzian transform makes sorting really simple and powerful

I hope you are not really using the Schwartzian transform in Rakudo as it is one of the worst ways to optimize a sort-by-generated-key operation!

Something as...

@keys = map gen_key($_), @data;
@sorted = @data[sort {$keys[$a] <=> $keys[$b]} 0..$#keys];
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should perform much better when correctly implemented in a low level language, specially if you are able to use packed arrays to store @keys.

Comment on Re: Perl 6 sorting (was: Re: Sort: By keys, values, and their returning values.) Download Code

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Re^2: Perl 6 sorting (was: Re: Sort: By keys, values, and their returning values.) by moritz (Cardinal) on Nov 26, 2009 at 12:37 UTC
I hope you are not really using the Schwartzian transform in Rakudo as it is one of the worst ways to optimize a sort-by-generated-key operation! Actually it's an implementation detail about which I don't care really much. Correctness first, performance later. I just called it a Schwartzian Transform because that's the name that most perl programmers use for the sort-by-generated-key operation. Looking at the source it seems to do something close to what you proposed. Perl 6 - links to (nearly) everything that is Perl 6.	[reply]

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Re^2: Perl 6 sorting (was: Re: Sort: By keys, values, and their returning values.)
by moritz (Cardinal) on Nov 26, 2009 at 12:37 UTC

I hope you are not really using the Schwartzian transform in Rakudo as it is one of the worst ways to optimize a sort-by-generated-key operation!

Actually it's an implementation detail about which I don't care really much. Correctness first, performance later. I just called it a Schwartzian Transform because that's the name that most perl programmers use for the sort-by-generated-key operation.

Looking at the source it seems to do something close to what you proposed.

Perl 6 - links to (nearly) everything that is Perl 6.

[reply]