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author | Jan Malakhovski <oxij@oxij.org> | 2017-12-07 21:26:30 +0000 |
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committer | Jan Malakhovski <oxij@oxij.org> | 2018-02-09 19:51:05 +0000 |
commit | ee3220440da59e39154b520353a3d03a1abf3405 (patch) | |
tree | aa3bf8018184d395869ffd2a32dd97632c2b100f /lib/lists.nix | |
parent | 2341c81427420be95cd9f8640e3e96e3e317c645 (diff) | |
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lib: implement `compare`, `splitByAndCompare`, and `compareLists`
Diffstat (limited to 'lib/lists.nix')
-rw-r--r-- | lib/lists.nix | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/lib/lists.nix b/lib/lists.nix index 8f67c6bb0ca..f7e09040a5a 100644 --- a/lib/lists.nix +++ b/lib/lists.nix @@ -385,6 +385,30 @@ rec { if len < 2 then list else (sort strictLess pivot.left) ++ [ first ] ++ (sort strictLess pivot.right)); + /* Compare two lists element-by-element. + + Example: + compareLists compare [] [] + => 0 + compareLists compare [] [ "a" ] + => -1 + compareLists compare [ "a" ] [] + => 1 + compareLists compare [ "a" "b" ] [ "a" "c" ] + => 1 + */ + compareLists = cmp: a: b: + if a == [] + then if b == [] + then 0 + else -1 + else if b == [] + then 1 + else let rel = cmp (head a) (head b); in + if rel == 0 + then compareLists cmp (tail a) (tail b) + else rel; + /* Return the first (at most) N elements of a list. Example: |