forked from lix-project/lix
499ed26508
it is out of date, all over the place in level of detail, is really about `nixpkgs`, and in general instructions should not be part of a reference manual. also: - update redirects and internal links - use "Nix language" consistently
7.4 KiB
7.4 KiB
Operators
The table below lists the operators in the Nix language, in order of precedence (from strongest to weakest binding).
| Name | Syntax | Associativity | Description | Precedence |
|---|---|---|---|---|
| Select | e . attrpath [ or def ] |
none | Select attribute denoted by the attribute path attrpath from set e. (An attribute path is a dot-separated list of attribute names.) If the attribute doesn’t exist, return def if provided, otherwise abort evaluation. | 1 |
| Application | e1 e2 | left | Call function e1 with argument e2. | 2 |
| Arithmetic Negation | - e |
none | Arithmetic negation. | 3 |
| Has Attribute | e ? attrpath |
none | Test whether set e contains the attribute denoted by attrpath; return true or false. |
4 |
| List Concatenation | e1 ++ e2 |
right | List concatenation. | 5 |
| Multiplication | e1 * e2, |
left | Arithmetic multiplication. | 6 |
| Division | e1 / e2 |
left | Arithmetic division. | 6 |
| Addition | e1 + e2 |
left | Arithmetic addition. | 7 |
| Subtraction | e1 - e2 |
left | Arithmetic subtraction. | 7 |
| String Concatenation | string1 + string2 |
left | String concatenation. | 7 |
| Not | ! e |
none | Boolean negation. | 8 |
| Update | e1 // e2 |
right | Return a set consisting of the attributes in e1 and e2 (with the latter taking precedence over the former in case of equally named attributes). | 9 |
| Less Than | e1 < e2, |
none | Arithmetic/lexicographic comparison. | 10 |
| Less Than or Equal To | e1 <= e2 |
none | Arithmetic/lexicographic comparison. | 10 |
| Greater Than | e1 > e2 |
none | Arithmetic/lexicographic comparison. | 10 |
| Greater Than or Equal To | e1 >= e2 |
none | Arithmetic/lexicographic comparison. | 10 |
| Equality | e1 == e2 |
none | Equality. | 11 |
| Inequality | e1 != e2 |
none | Inequality. | 11 |
| Logical AND | e1 && e2 |
left | Logical AND. | 12 |
| Logical OR | e1 || e2 |
left | Logical OR. | 13 |
| Logical Implication | e1 -> e2 |
none | Logical implication (equivalent to !e1 || e2). |
14 |