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lib.lists.unique: Switch from recursive function to using a fold

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This improves performance by ~30-40% for smaller test cases and makes
larger cases where my laptop would OOM pass in seconds.
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adisbladis 2020-11-24 06:20:01 +01:00
parent 8d8532cd32
commit 85605c8a29
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1 changed files with 1 additions and 7 deletions
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8
lib/lists.nix
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@ -640,13 +640,7 @@ rec {
unique [ 3 2 3 4 ] unique [ 3 2 3 4 ]
=> [ 3 2 4 ] => [ 3 2 4 ]
*/ */
unique = list: unique = foldl' (acc: e: if elem e acc then acc else acc ++ [ e ]) [];
if list == [] then
[]
else
let
x = head list;
in [x] ++ unique (remove x list);
/* Intersects list 'e' and another list. O(nm) complexity. /* Intersects list 'e' and another list. O(nm) complexity.