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intersperse: Fix quadratic performance

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This commit is contained in:
Eelco Dolstra 2015-07-24 15:55:39 +02:00
parent 2d9885db9e
commit c399f94bb3
1 changed files with 4 additions and 5 deletions
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9
lib/strings.nix
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@ -29,8 +29,7 @@ rec {
intersperse = separator: list: intersperse = separator: list:
if list == [] || length list == 1 if list == [] || length list == 1
then list then list
else [(head list) separator] else tail (lib.concatMap (x: [separator x]) list);
++ (intersperse separator (tail list));
# Concatenate a list of strings with a separator between each element, e.g. # Concatenate a list of strings with a separator between each element, e.g.
@ -128,9 +127,9 @@ rec {
addContextFrom = a: b: substring 0 0 a + b; addContextFrom = a: b: substring 0 0 a + b;
# Cut a string with a separator and produces a list of strings which were # Cut a string with a separator and produces a list of strings which
# separated by this separator. e.g., # were separated by this separator; e.g., `splitString "."
# `splitString "." "foo.bar.baz"' returns ["foo" "bar" "baz"]. # "foo.bar.baz"' returns ["foo" "bar" "baz"].
splitString = _sep: _s: splitString = _sep: _s:
let let
sep = addContextFrom _s _sep; sep = addContextFrom _s _sep;