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max-key and min-key evaluate k multiple times for arguments

Description

max-key or min-key will evaluate (k value) multiple times for arguments if more than 2 arguments are passed. This is undesirable if k is expensive to calculate.

Good perf test:

Approach: Avoid repeated evaluation of k for any element.

A criterium test of the example above shows:

  • Before: 206.017411 µs

  • After: 126.532306 µs

Patch: clj-99-v3.patch

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Michael Blume November 4, 2015 at 1:52 AM

clj-99-v3.patch behaves correctly for collection elements that are nil or false.

Michael Blume February 9, 2015 at 8:50 PM

clj-99-v2 applies cleanly to master

import April 11, 2014 at 5:47 PM

Comment made by: stevemkim

I created [CLJ-1402] for sort-by

Alex Miller April 11, 2014 at 4:50 PM

Separate.

import April 11, 2014 at 4:48 PM

Comment made by: stevemkim

sort-by is similarly inefficient. It calls keyfn for every comparison in sort, not once for every element to be sorted.

I'm not familiar with this project's preferred workflow, so I have to ask: Do you want me to open a separate ticket for sort-by, or do you prefer to consolidate that issue into this ticket?

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Created June 17, 2009 at 9:49 PM
Updated September 6, 2017 at 5:42 PM
Resolved September 6, 2017 at 5:42 PM