lib/attrsets: introduce mapCartesianProduct

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Gabriel Volpe 2024-04-15 19:16:15 +02:00
parent 10517cf9ab
commit fe2bead78b
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3 changed files with 60 additions and 1 deletions

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@ -913,6 +913,40 @@ rec {
) [{}] (attrNames attrsOfLists);
/**
Return the result of function f applied to the cartesian product of attribute set value combinations.
Equivalent to using cartesianProduct followed by map.
# Inputs
`f`
: A function, given an attribute set, it returns a new value.
`attrsOfLists`
: Attribute set with attributes that are lists of values
# Type
```
mapCartesianProduct :: (AttrSet -> a) -> AttrSet -> [a]
```
# Examples
:::{.example}
## `lib.attrsets.mapCartesianProduct` usage example
```nix
mapCartesianProduct ({a, b}: "${a}-${b}") { a = [ "1" "2" ]; b = [ "3" "4" ]; }
=> [ "1-3" "1-4" "2-3" "2-4" ]
```
:::
*/
mapCartesianProduct = f: attrsOfLists: map f (cartesianProduct attrsOfLists);
/**
Utility function that creates a `{name, value}` pair as expected by `builtins.listToAttrs`.

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@ -87,7 +87,7 @@ let
recursiveUpdate matchAttrs mergeAttrsList overrideExisting showAttrPath getOutput
getBin getLib getDev getMan chooseDevOutputs zipWithNames zip
recurseIntoAttrs dontRecurseIntoAttrs cartesianProduct cartesianProductOfSets
updateManyAttrsByPath;
mapCartesianProduct updateManyAttrsByPath;
inherit (self.lists) singleton forEach foldr fold foldl foldl' imap0 imap1
concatMap flatten remove findSingle findFirst any all count
optional optionals toList range replicate partition zipListsWith zipLists

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@ -71,6 +71,7 @@ let
makeIncludePath
makeOverridable
mapAttrs
mapCartesianProduct
matchAttrs
mergeAttrs
meta
@ -1753,6 +1754,30 @@ runTests {
];
};
testMapCartesianProductOfOneSet = {
expr = mapCartesianProduct ({a}: a * 2) { a = [ 1 2 3 ]; };
expected = [ 2 4 6 ];
};
testMapCartesianProductOfTwoSets = {
expr = mapCartesianProduct ({a,b}: a + b) { a = [ 1 ]; b = [ 10 20 ]; };
expected = [ 11 21 ];
};
testMapCartesianProcutOfTwoSetsWithOneEmpty = {
expr = mapCartesianProduct (x: x.a + x.b) { a = [ ]; b = [ 10 20 ]; };
expected = [ ];
};
testMapCartesianProductOfThreeSets = {
expr = mapCartesianProduct ({a,b,c}: a + b + c) {
a = [ 1 2 3 ];
b = [ 10 20 30 ];
c = [ 100 200 300 ];
};
expected = [ 111 211 311 121 221 321 131 231 331 112 212 312 122 222 322 132 232 332 113 213 313 123 223 323 133 233 333 ];
};
# The example from the showAttrPath documentation
testShowAttrPathExample = {
expr = showAttrPath [ "foo" "10" "bar" ];