forked from lix-project/lix
33 lines
7.1 KiB
Markdown
33 lines
7.1 KiB
Markdown
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# Operators
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[table\_title](#table-operators) lists the operators in the Nix
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expression language, in order of precedence (from strongest to weakest
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binding).
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| Name | Syntax | Associativity | Description | Precedence |
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| ------------------------ | ----------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- |
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| 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 |
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| Application | e1 e2 | left | Call function e1 with argument e2. | 2 |
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| Arithmetic Negation | `-` e | none | Arithmetic negation. | 3 |
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| Has Attribute | e `?` attrpath | none | Test whether set e contains the attribute denoted by attrpath; return `true` or `false`. | 4 |
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| List Concatenation | e1 `++` e2 | right | List concatenation. | 5 |
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| Multiplication | e1 `*` e2, | left | Arithmetic multiplication. | 6 |
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| Division | e1 `/` e2 | left | Arithmetic division. | 6 |
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| Addition | e1 `+` e2 | left | Arithmetic addition. | 7 |
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| Subtraction | e1 `-` e2 | left | Arithmetic subtraction. | 7 |
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| String Concatenation | string1 `+` string2 | left | String concatenation. | 7 |
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| Not | `!` e | none | Boolean negation. | 8 |
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| 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 |
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| Less Than | e1 `<` e2, | none | Arithmetic comparison. | 10 |
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| Less Than or Equal To | e1 `<=` e2 | none | Arithmetic comparison. | 10 |
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| Greater Than | e1 `>` e2 | none | Arithmetic comparison. | 10 |
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| Greater Than or Equal To | e1 `>=` e2 | none | Arithmetic comparison. | 10 |
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| Equality | e1 `==` e2 | none | Equality. | 11 |
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| Inequality | e1 `!=` e2 | none | Inequality. | 11 |
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| Logical AND | e1 `&&` e2 | left | Logical AND. | 12 |
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| Logical OR | e1 `\|\|` e2 | left | Logical OR. | 13 |
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| Logical Implication | e1 `->` e2 | none | Logical implication (equivalent to `!e1 \|\|
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e2`). | 14 |
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Operators
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