pyrox.dev
Merge pull request #274022 from hercules-ci/doc-attrsets-operators
lib/attrsets: Document and link Nix language operators
authored by Silvan Mosberger and committed by GitHub 5027eafc a931a220
+24
lib/attrsets.nix
+24
lib/attrsets.nix
···
14
14
15
15
/* Return an attribute from nested attribute sets.
16
16
17
+
Nix has an [attribute selection operator `. or`](https://nixos.org/manual/nix/stable/language/operators#attribute-selection) which is sufficient for such queries, as long as the number of attributes is static. For example:
18
+
19
+
```nix
20
+
(x.a.b or 6) == attrByPath ["a" "b"] 6 x
21
+
# and
22
+
(x.${f p}."example.com" or 6) == attrByPath [ (f p) "example.com" ] 6 x
23
+
```
24
+
17
25
Example:
18
26
x = { a = { b = 3; }; }
19
27
# ["a" "b"] is equivalent to x.a.b
···
50
58
attrByPath' 0 set;
51
59
52
60
/* Return if an attribute from nested attribute set exists.
61
+
62
+
Nix has a [has attribute operator `?`](https://nixos.org/manual/nix/stable/language/operators#has-attribute), which is sufficient for such queries, as long as the number of attributes is static. For example:
63
+
64
+
```nix
65
+
(x?a.b) == hasAttryByPath ["a" "b"] x
66
+
# and
67
+
(x?${f p}."example.com") == hasAttryByPath [ (f p) "example.com" ] x
68
+
```
53
69
54
70
**Laws**:
55
71
1. ```nix
···
176
192
177
193
/* Like `attrByPath`, but without a default value. If it doesn't find the
178
194
path it will throw an error.
195
+
196
+
Nix has an [attribute selection operator](https://nixos.org/manual/nix/stable/language/operators#attribute-selection) which is sufficient for such queries, as long as the number of attributes is static. For example:
197
+
198
+
```nix
199
+
x.a.b == getAttrByPath ["a" "b"] x
200
+
# and
201
+
x.${f p}."example.com" == getAttrByPath [ (f p) "example.com" ] x
202
+
```
179
203
180
204
Example:
181
205
x = { a = { b = 3; }; }