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noogle/pesto/test_data/assets/attrsets.nix
hsjobeki effa51cb39
add alias tracking and bulk tests
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{ lib }:
# Operations on attribute sets.
let
inherit (builtins) head tail length;
inherit (lib.trivial) id mergeAttrs;
inherit (lib.strings) concatStringsSep concatMapStringsSep escapeNixIdentifier sanitizeDerivationName;
inherit (lib.lists) foldr foldl' concatMap concatLists elemAt all partition groupBy take foldl;
in
rec {
inherit (builtins) attrNames listToAttrs hasAttr isAttrs getAttr removeAttrs;
/**
Return an attribute from nested attribute sets.
# Example
```nix
x = { a = { b = 3; }; }
# ["a" "b"] is equivalent to x.a.b
# 6 is a default value to return if the path does not exist in attrset
attrByPath ["a" "b"] 6 x
=> 3
attrByPath ["z" "z"] 6 x
=> 6
```
# Type
```
attrByPath :: [String] -> Any -> AttrSet -> Any
```
# Arguments
- [attrPath] A list of strings representing the attribute path to return from `set`
- [default] Default value if `attrPath` does not resolve to an existing value
- [set] The nested attribute set to select values from
*/
attrByPath =
# A list of strings representing the attribute path to return from `set`
attrPath:
# Default value if `attrPath` does not resolve to an existing value
default:
# The nested attribute set to select values from
set:
let attr = head attrPath;
in
if attrPath == [] then set
else if set ? ${attr}
then attrByPath (tail attrPath) default set.${attr}
else default;
/**
Return if an attribute from nested attribute set exists.
# Example
```nix
x = { a = { b = 3; }; }
hasAttrByPath ["a" "b"] x
=> true
hasAttrByPath ["z" "z"] x
=> false
```
# Type
```
hasAttrByPath :: [String] -> AttrSet -> Bool
```
# Arguments
- [attrPath] A list of strings representing the attribute path to check from `set`
- [e] The nested attribute set to check
*/
hasAttrByPath =
# A list of strings representing the attribute path to check from `set`
attrPath:
# The nested attribute set to check
e:
let attr = head attrPath;
in
if attrPath == [] then true
else if e ? ${attr}
then hasAttrByPath (tail attrPath) e.${attr}
else false;
/**
Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.
# Example
```nix
setAttrByPath ["a" "b"] 3
=> { a = { b = 3; }; }
```
# Type
```
setAttrByPath :: [String] -> Any -> AttrSet
```
# Arguments
- [attrPath] A list of strings representing the attribute path to set
- [value] The value to set at the location described by `attrPath`
*/
setAttrByPath =
# A list of strings representing the attribute path to set
attrPath:
# The value to set at the location described by `attrPath`
value:
let
len = length attrPath;
atDepth = n:
if n == len
then value
else { ${elemAt attrPath n} = atDepth (n + 1); };
in atDepth 0;
/**
Like `attrByPath`, but without a default value. If it doesn't find the
path it will throw an error.
# Example
```nix
x = { a = { b = 3; }; }
getAttrFromPath ["a" "b"] x
=> 3
getAttrFromPath ["z" "z"] x
=> error: cannot find attribute `z.z'
```
# Type
```
getAttrFromPath :: [String] -> AttrSet -> Any
```
# Arguments
- [attrPath] A list of strings representing the attribute path to get from `set`
- [set] The nested attribute set to find the value in.
*/
getAttrFromPath =
# A list of strings representing the attribute path to get from `set`
attrPath:
# The nested attribute set to find the value in.
set:
let errorMsg = "cannot find attribute `" + concatStringsSep "." attrPath + "'";
in attrByPath attrPath (abort errorMsg) set;
/**
Map each attribute in the given set and merge them into a new attribute set.
# Example
```nix
concatMapAttrs
(name: value: {
${name} = value;
${name + value} = value;
})
{ x = "a"; y = "b"; }
=> { x = "a"; xa = "a"; y = "b"; yb = "b"; }
```
# Type
```
concatMapAttrs :: (String -> a -> AttrSet) -> AttrSet -> AttrSet
```
# Arguments
- [f]
- [v]
*/
concatMapAttrs = f: v:
foldl' mergeAttrs { }
(attrValues
(mapAttrs f v)
);
/**
Update or set specific paths of an attribute set.
Takes a list of updates to apply and an attribute set to apply them to,
and returns the attribute set with the updates applied. Updates are
represented as `{ path = ...; update = ...; }` values, where `path` is a
list of strings representing the attribute path that should be updated,
and `update` is a function that takes the old value at that attribute path
as an argument and returns the new
value it should be.
Properties:
- Updates to deeper attribute paths are applied before updates to more
shallow attribute paths
- Multiple updates to the same attribute path are applied in the order
they appear in the update list
- If any but the last `path` element leads into a value that is not an
attribute set, an error is thrown
- If there is an update for an attribute path that doesn't exist,
accessing the argument in the update function causes an error, but
intermediate attribute sets are implicitly created as needed
# Example
```nix
updateManyAttrsByPath [
{
path = [ "a" "b" ];
update = old: { d = old.c; };
}
{
path = [ "a" "b" "c" ];
update = old: old + 1;
}
{
path = [ "x" "y" ];
update = old: "xy";
}
] { a.b.c = 0; }
=> { a = { b = { d = 1; }; }; x = { y = "xy"; }; }
```
# Type
```
updateManyAttrsByPath :: [{ path :: [String]; update :: (Any -> Any); }] -> AttrSet -> AttrSet
```
*/
updateManyAttrsByPath = let
# When recursing into attributes, instead of updating the `path` of each
# update using `tail`, which needs to allocate an entirely new list,
# we just pass a prefix length to use and make sure to only look at the
# path without the prefix length, so that we can reuse the original list
# entries.
go = prefixLength: hasValue: value: updates:
let
# Splits updates into ones on this level (split.right)
# And ones on levels further down (split.wrong)
split = partition (el: length el.path == prefixLength) updates;
# Groups updates on further down levels into the attributes they modify
nested = groupBy (el: elemAt el.path prefixLength) split.wrong;
# Applies only nested modification to the input value
withNestedMods =
# Return the value directly if we don't have any nested modifications
if split.wrong == [] then
if hasValue then value
else
# Throw an error if there is no value. This `head` call here is
# safe, but only in this branch since `go` could only be called
# with `hasValue == false` for nested updates, in which case
# it's also always called with at least one update
let updatePath = (head split.right).path; in
throw
( "updateManyAttrsByPath: Path '${showAttrPath updatePath}' does "
+ "not exist in the given value, but the first update to this "
+ "path tries to access the existing value.")
else
# If there are nested modifications, try to apply them to the value
if ! hasValue then
# But if we don't have a value, just use an empty attribute set
# as the value, but simplify the code a bit
mapAttrs (name: go (prefixLength + 1) false null) nested
else if isAttrs value then
# If we do have a value and it's an attribute set, override it
# with the nested modifications
value //
mapAttrs (name: go (prefixLength + 1) (value ? ${name}) value.${name}) nested
else
# However if it's not an attribute set, we can't apply the nested
# modifications, throw an error
let updatePath = (head split.wrong).path; in
throw
( "updateManyAttrsByPath: Path '${showAttrPath updatePath}' needs to "
+ "be updated, but path '${showAttrPath (take prefixLength updatePath)}' "
+ "of the given value is not an attribute set, so we can't "
+ "update an attribute inside of it.");
# We get the final result by applying all the updates on this level
# after having applied all the nested updates
# We use foldl instead of foldl' so that in case of multiple updates,
# intermediate values aren't evaluated if not needed
in foldl (acc: el: el.update acc) withNestedMods split.right;
in updates: value: go 0 true value updates;
/**
Return the specified attributes from a set.
# Example
```nix
attrVals ["a" "b" "c"] as
=> [as.a as.b as.c]
```
# Type
```
attrVals :: [String] -> AttrSet -> [Any]
```
# Arguments
- [nameList] The list of attributes to fetch from `set`. Each attribute name must exist on the attrbitue set
- [set] The set to get attribute values from
*/
attrVals =
# The list of attributes to fetch from `set`. Each attribute name must exist on the attrbitue set
nameList:
# The set to get attribute values from
set: map (x: set.${x}) nameList;
/**
Return the values of all attributes in the given set, sorted by
attribute name.
# Example
```nix
attrValues {c = 3; a = 1; b = 2;}
=> [1 2 3]
```
# Type
```
attrValues :: AttrSet -> [Any]
```
*/
attrValues = builtins.attrValues or (attrs: attrVals (attrNames attrs) attrs);
/**
Given a set of attribute names, return the set of the corresponding
attributes from the given set.
# Example
```nix
getAttrs [ "a" "b" ] { a = 1; b = 2; c = 3; }
=> { a = 1; b = 2; }
```
# Type
```
getAttrs :: [String] -> AttrSet -> AttrSet
```
# Arguments
- [names] A list of attribute names to get out of `set`
- [attrs] The set to get the named attributes from
*/
getAttrs =
# A list of attribute names to get out of `set`
names:
# The set to get the named attributes from
attrs: genAttrs names (name: attrs.${name});
/**
Collect each attribute named `attr` from a list of attribute
sets. Sets that don't contain the named attribute are ignored.
# Example
```nix
catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}]
=> [1 2]
```
# Type
```
catAttrs :: String -> [AttrSet] -> [Any]
```
*/
catAttrs = builtins.catAttrs or
(attr: l: concatLists (map (s: if s ? ${attr} then [s.${attr}] else []) l));
/**
Filter an attribute set by removing all attributes for which the
given predicate return false.
# Example
```nix
filterAttrs (n: v: n == "foo") { foo = 1; bar = 2; }
=> { foo = 1; }
```
# Type
```
filterAttrs :: (String -> Any -> Bool) -> AttrSet -> AttrSet
```
# Arguments
- [pred] Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
- [set] The attribute set to filter
*/
filterAttrs =
# Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
pred:
# The attribute set to filter
set:
listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));
/**
Filter an attribute set recursively by removing all attributes for
which the given predicate return false.
# Example
```nix
filterAttrsRecursive (n: v: v != null) { foo = { bar = null; }; }
=> { foo = {}; }
```
# Type
```
filterAttrsRecursive :: (String -> Any -> Bool) -> AttrSet -> AttrSet
```
# Arguments
- [pred] Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
- [set] The attribute set to filter
*/
filterAttrsRecursive =
# Predicate taking an attribute name and an attribute value, which returns `true` to include the attribute, or `false` to exclude the attribute.
pred:
# The attribute set to filter
set:
listToAttrs (
concatMap (name:
let v = set.${name}; in
if pred name v then [
(nameValuePair name (
if isAttrs v then filterAttrsRecursive pred v
else v
))
] else []
) (attrNames set)
);
/**
Like [`lib.lists.foldl'`](#function-library-lib.lists.foldl-prime) but for attribute sets.
Iterates over every name-value pair in the given attribute set.
The result of the callback function is often called `acc` for accumulator. It is passed between callbacks from left to right and the final `acc` is the return value of `foldlAttrs`.
Attention:
There is a completely different function
`lib.foldAttrs`
which has nothing to do with this function, despite the similar name.
# Example
```nix
foldlAttrs
(acc: name: value: {
sum = acc.sum + value;
names = acc.names ++ [name];
})
{ sum = 0; names = []; }
{
foo = 1;
bar = 10;
}
->
{
sum = 11;
names = ["bar" "foo"];
}
foldlAttrs
(throw "function not needed")
123
{};
->
123
foldlAttrs
(acc: _: _: acc)
3
{ z = throw "value not needed"; a = throw "value not needed"; };
->
3
The accumulator doesn't have to be an attrset.
It can be as simple as a number or string.
foldlAttrs
(acc: _: v: acc * 10 + v)
1
{ z = 1; a = 2; };
->
121
```
# Type
```
foldlAttrs :: ( a -> String -> b -> a ) -> a -> { ... :: b } -> a
```
# Arguments
- [f]
- [init]
- [set]
*/
foldlAttrs = f: init: set:
foldl'
(acc: name: f acc name set.${name})
init
(attrNames set);
/**
Apply fold functions to values grouped by key.
# Example
```nix
foldAttrs (item: acc: [item] ++ acc) [] [{ a = 2; } { a = 3; }]
=> { a = [ 2 3 ]; }
```
# Type
```
foldAttrs :: (Any -> Any -> Any) -> Any -> [AttrSets] -> Any
```
# Arguments
- [op] A function, given a value and a collector combines the two.
- [nul] The starting value.
- [list_of_attrs] A list of attribute sets to fold together by key.
*/
foldAttrs =
# A function, given a value and a collector combines the two.
op:
# The starting value.
nul:
# A list of attribute sets to fold together by key.
list_of_attrs:
foldr (n: a:
foldr (name: o:
o // { ${name} = op n.${name} (a.${name} or nul); }
) a (attrNames n)
) {} list_of_attrs;
/**
Recursively collect sets that verify a given predicate named `pred`
from the set `attrs`. The recursion is stopped when the predicate is
verified.
# Example
```nix
collect isList { a = { b = ["b"]; }; c = [1]; }
=> [["b"] [1]]
collect (x: x ? outPath)
{ a = { outPath = "a/"; }; b = { outPath = "b/"; }; }
=> [{ outPath = "a/"; } { outPath = "b/"; }]
```
# Type
```
collect :: (AttrSet -> Bool) -> AttrSet -> [x]
```
# Arguments
- [pred] Given an attribute's value, determine if recursion should stop.
- [attrs] The attribute set to recursively collect.
*/
collect =
# Given an attribute's value, determine if recursion should stop.
pred:
# The attribute set to recursively collect.
attrs:
if pred attrs then
[ attrs ]
else if isAttrs attrs then
concatMap (collect pred) (attrValues attrs)
else
[];
/**
Return the cartesian product of attribute set value combinations.
# Example
```nix
cartesianProductOfSets { a = [ 1 2 ]; b = [ 10 20 ]; }
=> [
{ a = 1; b = 10; }
{ a = 1; b = 20; }
{ a = 2; b = 10; }
{ a = 2; b = 20; }
]
```
# Type
```
cartesianProductOfSets :: AttrSet -> [AttrSet]
```
# Arguments
- [attrsOfLists] Attribute set with attributes that are lists of values
*/
cartesianProductOfSets =
# Attribute set with attributes that are lists of values
attrsOfLists:
foldl' (listOfAttrs: attrName:
concatMap (attrs:
map (listValue: attrs // { ${attrName} = listValue; }) attrsOfLists.${attrName}
) listOfAttrs
) [{}] (attrNames attrsOfLists);
/**
Utility function that creates a `{name, value}` pair as expected by `builtins.listToAttrs`.
# Example
```nix
nameValuePair "some" 6
=> { name = "some"; value = 6; }
```
# Type
```
nameValuePair :: String -> Any -> { name :: String; value :: Any; }
```
# Arguments
- [name] Attribute name
- [value] Attribute value
*/
nameValuePair =
# Attribute name
name:
# Attribute value
value:
{ inherit name value; };
/**
Apply a function to each element in an attribute set, creating a new attribute set.
# Example
```nix
mapAttrs (name: value: name + "-" + value)
{ x = "foo"; y = "bar"; }
=> { x = "x-foo"; y = "y-bar"; }
```
# Type
```
mapAttrs :: (String -> Any -> Any) -> AttrSet -> AttrSet
```
*/
mapAttrs = builtins.mapAttrs or
(f: set:
listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set)));
/**
Like `mapAttrs`, but allows the name of each attribute to be
changed in addition to the value. The applied function should
return both the new name and value as a `nameValuePair`.
# Example
```nix
mapAttrs' (name: value: nameValuePair ("foo_" + name) ("bar-" + value))
{ x = "a"; y = "b"; }
=> { foo_x = "bar-a"; foo_y = "bar-b"; }
```
# Type
```
mapAttrs' :: (String -> Any -> { name :: String; value :: Any; }) -> AttrSet -> AttrSet
```
# Arguments
- [f] A function, given an attribute's name and value, returns a new `nameValuePair`.
- [set] Attribute set to map over.
*/
mapAttrs' =
# A function, given an attribute's name and value, returns a new `nameValuePair`.
f:
# Attribute set to map over.
set:
listToAttrs (map (attr: f attr set.${attr}) (attrNames set));
/**
Call a function for each attribute in the given set and return
the result in a list.
# Example
```nix
mapAttrsToList (name: value: name + value)
{ x = "a"; y = "b"; }
=> [ "xa" "yb" ]
```
# Type
```
mapAttrsToList :: (String -> a -> b) -> AttrSet -> [b]
```
# Arguments
- [f] A function, given an attribute's name and value, returns a new value.
- [attrs] Attribute set to map over.
*/
mapAttrsToList =
# A function, given an attribute's name and value, returns a new value.
f:
# Attribute set to map over.
attrs:
map (name: f name attrs.${name}) (attrNames attrs);
/**
Deconstruct an attrset to a list of name-value pairs as expected by [`builtins.listToAttrs`](https://nixos.org/manual/nix/stable/language/builtins.html#builtins-listToAttrs).
Each element of the resulting list is an attribute set with these attributes:
- `name` (string): The name of the attribute
- `value` (any): The value of the attribute
The following is always true:
```nix
builtins.listToAttrs (attrsToList attrs) == attrs
```
:::{.warning}
The opposite is not always true. In general expect that
```nix
attrsToList (builtins.listToAttrs list) != list
```
This is because the `listToAttrs` removes duplicate names and doesn't preserve the order of the list.
:::
# Example
```nix
attrsToList { foo = 1; bar = "asdf"; }
=> [ { name = "bar"; value = "asdf"; } { name = "foo"; value = 1; } ]
```
# Type
```
attrsToList :: AttrSet -> [ { name :: String; value :: Any; } ]
```
*/
attrsToList = mapAttrsToList nameValuePair;
/**
Like `mapAttrs`, except that it recursively applies itself to
the *leaf* attributes of a potentially-nested attribute set:
the second argument of the function will never be an attrset.
Also, the first argument of the argument function is a *list*
of the attribute names that form the path to the leaf attribute.
For a function that gives you control over what counts as a leaf,
see `mapAttrsRecursiveCond`.
# Example
```nix
mapAttrsRecursive (path: value: concatStringsSep "-" (path ++ [value]))
{ n = { a = "A"; m = { b = "B"; c = "C"; }; }; d = "D"; }
=> { n = { a = "n-a-A"; m = { b = "n-m-b-B"; c = "n-m-c-C"; }; }; d = "d-D"; }
```
# Type
```
mapAttrsRecursive :: ([String] -> a -> b) -> AttrSet -> AttrSet
```
# Arguments
- [f] A function, given a list of attribute names and a value, returns a new value.
- [set] Set to recursively map over.
*/
mapAttrsRecursive =
# A function, given a list of attribute names and a value, returns a new value.
f:
# Set to recursively map over.
set:
mapAttrsRecursiveCond (as: true) f set;
/**
Like `mapAttrsRecursive`, but it takes an additional predicate
function that tells it whether to recurse into an attribute
set. If it returns false, `mapAttrsRecursiveCond` does not
recurse, but does apply the map function. If it returns true, it
does recurse, and does not apply the map function.
# Example
```nix
# To prevent recursing into derivations (which are attribute
# sets with the attribute "type" equal to "derivation"):
mapAttrsRecursiveCond
(as: !(as ? "type" && as.type == "derivation"))
(x: ... do something ...)
attrs
```
# Type
```
mapAttrsRecursiveCond :: (AttrSet -> Bool) -> ([String] -> a -> b) -> AttrSet -> AttrSet
```
# Arguments
- [cond] A function, given the attribute set the recursion is currently at, determine if to recurse deeper into that attribute set.
- [f] A function, given a list of attribute names and a value, returns a new value.
- [set] Attribute set to recursively map over.
*/
mapAttrsRecursiveCond =
# A function, given the attribute set the recursion is currently at, determine if to recurse deeper into that attribute set.
cond:
# A function, given a list of attribute names and a value, returns a new value.
f:
# Attribute set to recursively map over.
set:
let
recurse = path:
let
g =
name: value:
if isAttrs value && cond value
then recurse (path ++ [name]) value
else f (path ++ [name]) value;
in mapAttrs g;
in recurse [] set;
/**
Generate an attribute set by mapping a function over a list of
attribute names.
# Example
```nix
genAttrs [ "foo" "bar" ] (name: "x_" + name)
=> { foo = "x_foo"; bar = "x_bar"; }
```
# Type
```
genAttrs :: [ String ] -> (String -> Any) -> AttrSet
```
# Arguments
- [names] Names of values in the resulting attribute set.
- [f] A function, given the name of the attribute, returns the attribute's value.
*/
genAttrs =
# Names of values in the resulting attribute set.
names:
# A function, given the name of the attribute, returns the attribute's value.
f:
listToAttrs (map (n: nameValuePair n (f n)) names);
/**
Check whether the argument is a derivation. Any set with
`{ type = "derivation"; }` counts as a derivation.
# Example
```nix
nixpkgs = import <nixpkgs> {}
isDerivation nixpkgs.ruby
=> true
isDerivation "foobar"
=> false
```
# Type
```
isDerivation :: Any -> Bool
```
# Arguments
- [value] Value to check.
*/
isDerivation =
# Value to check.
value: value.type or null == "derivation";
/**
Converts a store path to a fake derivation.
# Type
```
toDerivation :: Path -> Derivation
```
# Arguments
- [path] A store path to convert to a derivation.
*/
toDerivation =
# A store path to convert to a derivation.
path:
let
path' = builtins.storePath path;
res =
{ type = "derivation";
name = sanitizeDerivationName (builtins.substring 33 (-1) (baseNameOf path'));
outPath = path';
outputs = [ "out" ];
out = res;
outputName = "out";
};
in res;
/**
If `cond` is true, return the attribute set `as`,
otherwise an empty attribute set.
# Example
```nix
optionalAttrs (true) { my = "set"; }
=> { my = "set"; }
optionalAttrs (false) { my = "set"; }
=> { }
```
# Type
```
optionalAttrs :: Bool -> AttrSet -> AttrSet
```
# Arguments
- [cond] Condition under which the `as` attribute set is returned.
- [as] The attribute set to return if `cond` is `true`.
*/
optionalAttrs =
# Condition under which the `as` attribute set is returned.
cond:
# The attribute set to return if `cond` is `true`.
as:
if cond then as else {};
/**
Merge sets of attributes and use the function `f` to merge attributes
values.
# Example
```nix
zipAttrsWithNames ["a"] (name: vs: vs) [{a = "x";} {a = "y"; b = "z";}]
=> { a = ["x" "y"]; }
```
# Type
```
zipAttrsWithNames :: [ String ] -> (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet
```
# Arguments
- [names] List of attribute names to zip.
- [f] A function, accepts an attribute name, all the values, and returns a combined value.
- [sets] List of values from the list of attribute sets.
*/
zipAttrsWithNames =
# List of attribute names to zip.
names:
# A function, accepts an attribute name, all the values, and returns a combined value.
f:
# List of values from the list of attribute sets.
sets:
listToAttrs (map (name: {
inherit name;
value = f name (catAttrs name sets);
}) names);
/**
Merge sets of attributes and use the function f to merge attribute values.
Like `lib.attrsets.zipAttrsWithNames` with all key names are passed for `names`.
Implementation note: Common names appear multiple times in the list of
names, hopefully this does not affect the system because the maximal
laziness avoid computing twice the same expression and `listToAttrs` does
not care about duplicated attribute names.
# Example
```nix
zipAttrsWith (name: values: values) [{a = "x";} {a = "y"; b = "z";}]
=> { a = ["x" "y"]; b = ["z"]; }
```
# Type
```
zipAttrsWith :: (String -> [ Any ] -> Any) -> [ AttrSet ] -> AttrSet
```
*/
zipAttrsWith =
builtins.zipAttrsWith or (f: sets: zipAttrsWithNames (concatMap attrNames sets) f sets);
/**
Merge sets of attributes and combine each attribute value in to a list.
Like `lib.attrsets.zipAttrsWith` with `(name: values: values)` as the function.
# Example
```nix
zipAttrs [{a = "x";} {a = "y"; b = "z";}]
=> { a = ["x" "y"]; b = ["z"]; }
```
# Type
```
zipAttrs :: [ AttrSet ] -> AttrSet
```
# Arguments
- [sets] List of attribute sets to zip together.
*/
zipAttrs =
# List of attribute sets to zip together.
sets:
zipAttrsWith (name: values: values) sets;
/**
Merge a list of attribute sets together using the `//` operator.
In case of duplicate attributes, values from later list elements take precedence over earlier ones.
The result is the same as `foldl mergeAttrs { }`, but the performance is better for large inputs.
For n list elements, each with an attribute set containing m unique attributes, the complexity of this operation is O(nm log n).
# Example
```nix
mergeAttrsList [ { a = 0; b = 1; } { c = 2; d = 3; } ]
=> { a = 0; b = 1; c = 2; d = 3; }
mergeAttrsList [ { a = 0; } { a = 1; } ]
=> { a = 1; }
```
# Type
```
mergeAttrsList :: [ Attrs ] -> Attrs
```
# Arguments
- [list]
*/
mergeAttrsList = list:
let
# `binaryMerge start end` merges the elements at indices `index` of `list` such that `start <= index < end`
# Type: Int -> Int -> Attrs
binaryMerge = start: end:
# assert start < end; # Invariant
if end - start >= 2 then
# If there's at least 2 elements, split the range in two, recurse on each part and merge the result
# The invariant is satisfied because each half will have at least 1 element
binaryMerge start (start + (end - start) / 2)
// binaryMerge (start + (end - start) / 2) end
else
# Otherwise there will be exactly 1 element due to the invariant, in which case we just return it directly
elemAt list start;
in
if list == [ ] then
# Calling binaryMerge as below would not satisfy its invariant
{ }
else
binaryMerge 0 (length list);
/**
Does the same as the update operator '//' except that attributes are
merged until the given predicate is verified. The predicate should
accept 3 arguments which are the path to reach the attribute, a part of
the first attribute set and a part of the second attribute set. When
the predicate is satisfied, the value of the first attribute set is
replaced by the value of the second attribute set.
# Example
```nix
recursiveUpdateUntil (path: l: r: path == ["foo"]) {
# first attribute set
foo.bar = 1;
foo.baz = 2;
bar = 3;
} {
#second attribute set
foo.bar = 1;
foo.quz = 2;
baz = 4;
}
=> {
foo.bar = 1; # 'foo.*' from the second set
foo.quz = 2; #
bar = 3; # 'bar' from the first set
baz = 4; # 'baz' from the second set
}
```
# Type
```
recursiveUpdateUntil :: ( [ String ] -> AttrSet -> AttrSet -> Bool ) -> AttrSet -> AttrSet -> AttrSet
```
# Arguments
- [pred] Predicate, taking the path to the current attribute as a list of strings for attribute names, and the two values at that path from the original arguments.
- [lhs] Left attribute set of the merge.
- [rhs] Right attribute set of the merge.
*/
recursiveUpdateUntil =
# Predicate, taking the path to the current attribute as a list of strings for attribute names, and the two values at that path from the original arguments.
pred:
# Left attribute set of the merge.
lhs:
# Right attribute set of the merge.
rhs:
let f = attrPath:
zipAttrsWith (n: values:
let here = attrPath ++ [n]; in
if length values == 1
|| pred here (elemAt values 1) (head values) then
head values
else
f here values
);
in f [] [rhs lhs];
/**
A recursive variant of the update operator ‘//’. The recursion
stops when one of the attribute values is not an attribute set,
in which case the right hand side value takes precedence over the
left hand side value.
# Example
```nix
recursiveUpdate {
boot.loader.grub.enable = true;
boot.loader.grub.device = "/dev/hda";
} {
boot.loader.grub.device = "";
}
returns: {
boot.loader.grub.enable = true;
boot.loader.grub.device = "";
}
```
# Type
```
recursiveUpdate :: AttrSet -> AttrSet -> AttrSet
```
# Arguments
- [lhs] Left attribute set of the merge.
- [rhs] Right attribute set of the merge.
*/
recursiveUpdate =
# Left attribute set of the merge.
lhs:
# Right attribute set of the merge.
rhs:
recursiveUpdateUntil (path: lhs: rhs: !(isAttrs lhs && isAttrs rhs)) lhs rhs;
/**
Returns true if the pattern is contained in the set. False otherwise.
# Example
```nix
matchAttrs { cpu = {}; } { cpu = { bits = 64; }; }
=> true
```
# Type
```
matchAttrs :: AttrSet -> AttrSet -> Bool
```
# Arguments
- [pattern] Attribute set structure to match
- [attrs] Attribute set to find patterns in
*/
matchAttrs =
# Attribute set structure to match
pattern:
# Attribute set to find patterns in
attrs:
assert isAttrs pattern;
all id (attrValues (zipAttrsWithNames (attrNames pattern) (n: values:
let pat = head values; val = elemAt values 1; in
if length values == 1 then false
else if isAttrs pat then isAttrs val && matchAttrs pat val
else pat == val
) [pattern attrs]));
/**
Override only the attributes that are already present in the old set
useful for deep-overriding.
# Example
```nix
overrideExisting {} { a = 1; }
=> {}
overrideExisting { b = 2; } { a = 1; }
=> { b = 2; }
overrideExisting { a = 3; b = 2; } { a = 1; }
=> { a = 1; b = 2; }
```
# Type
```
overrideExisting :: AttrSet -> AttrSet -> AttrSet
```
# Arguments
- [old] Original attribute set
- [new] Attribute set with attributes to override in `old`.
*/
overrideExisting =
# Original attribute set
old:
# Attribute set with attributes to override in `old`.
new:
mapAttrs (name: value: new.${name} or value) old;
/**
Turns a list of strings into a human-readable description of those
strings represented as an attribute path. The result of this function is
not intended to be machine-readable.
Create a new attribute set with `value` set at the nested attribute location specified in `attrPath`.
# Example
```nix
showAttrPath [ "foo" "10" "bar" ]
=> "foo.\"10\".bar"
showAttrPath []
=> "<root attribute path>"
```
# Type
```
showAttrPath :: [String] -> String
```
# Arguments
- [path] Attribute path to render to a string
*/
showAttrPath =
# Attribute path to render to a string
path:
if path == [] then "<root attribute path>"
else concatMapStringsSep "." escapeNixIdentifier path;
/**
Get a package output.
If no output is found, fallback to `.out` and then to the default.
# Example
```nix
getOutput "dev" pkgs.openssl
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev"
```
# Type
```
getOutput :: String -> Derivation -> String
```
# Arguments
- [output]
- [pkg]
*/
getOutput = output: pkg:
if ! pkg ? outputSpecified || ! pkg.outputSpecified
then pkg.${output} or pkg.out or pkg
else pkg;
/**
Get a package's `bin` output.
If the output does not exist, fallback to `.out` and then to the default.
# Example
```nix
getBin pkgs.openssl
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r"
```
# Type
```
getBin :: Derivation -> String
```
*/
getBin = getOutput "bin";
/**
Get a package's `lib` output.
If the output does not exist, fallback to `.out` and then to the default.
# Example
```nix
getLib pkgs.openssl
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-lib"
```
# Type
```
getLib :: Derivation -> String
```
*/
getLib = getOutput "lib";
/**
Get a package's `dev` output.
If the output does not exist, fallback to `.out` and then to the default.
# Example
```nix
getDev pkgs.openssl
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-dev"
```
# Type
```
getDev :: Derivation -> String
```
*/
getDev = getOutput "dev";
/**
Get a package's `man` output.
If the output does not exist, fallback to `.out` and then to the default.
# Example
```nix
getMan pkgs.openssl
=> "/nix/store/9rz8gxhzf8sw4kf2j2f1grr49w8zx5vj-openssl-1.0.1r-man"
```
# Type
```
getMan :: Derivation -> String
```
*/
getMan = getOutput "man";
/**
Pick the outputs of packages to place in `buildInputs`
# Type
```
chooseDevOutputs :: [Derivation] -> [String]
```
# Arguments
- [drvs] List of packages to pick `dev` outputs from
*/
chooseDevOutputs =
# List of packages to pick `dev` outputs from
drvs:
builtins.map getDev drvs;
/**
Make various Nix tools consider the contents of the resulting
attribute set when looking for what to build, find, etc.
This function only affects a single attribute set; it does not
apply itself recursively for nested attribute sets.
# Example
```nix
{ pkgs ? import <nixpkgs> {} }:
{
myTools = pkgs.lib.recurseIntoAttrs {
inherit (pkgs) hello figlet;
};
}
```
# Type
```
recurseIntoAttrs :: AttrSet -> AttrSet
```
# Arguments
- [attrs] An attribute set to scan for derivations.
*/
recurseIntoAttrs =
# An attribute set to scan for derivations.
attrs:
attrs // { recurseForDerivations = true; };
/**
Undo the effect of recurseIntoAttrs.
# Type
```
dontRecurseIntoAttrs :: AttrSet -> AttrSet
```
# Arguments
- [attrs] An attribute set to not scan for derivations.
*/
dontRecurseIntoAttrs =
# An attribute set to not scan for derivations.
attrs:
attrs // { recurseForDerivations = false; };
/**
`unionOfDisjoint x y` is equal to `x // y // z` where the
attrnames in `z` are the intersection of the attrnames in `x` and
`y`, and all values `assert` with an error message. This
operator is commutative, unlike (//).
# Type
```
unionOfDisjoint :: AttrSet -> AttrSet -> AttrSet
```
# Arguments
- [x]
- [y]
*/
unionOfDisjoint = x: y:
let
intersection = builtins.intersectAttrs x y;
collisions = lib.concatStringsSep " " (builtins.attrNames intersection);
mask = builtins.mapAttrs (name: value: builtins.throw
"unionOfDisjoint: collision on ${name}; complete list: ${collisions}")
intersection;
in
(x // y) // mask;
# DEPRECATED
zipWithNames = zipAttrsWithNames;
# DEPRECATED
zip = builtins.trace
"lib.zip is deprecated, use lib.zipAttrsWith instead" zipAttrsWith;
}
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