forked from lix-project/lix
09471d2680
Makes lists comparable using lexicographic comparison. Increments builtins.langVersion in order for this change to be detectable
29 lines
7.4 KiB
Markdown
29 lines
7.4 KiB
Markdown
# Operators
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The table below lists the operators in the Nix expression language, in
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order of precedence (from strongest to weakest 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/lexicographic comparison. | 10 |
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| Less Than or Equal To | *e1* `<=` *e2* | none | Arithmetic/lexicographic comparison. | 10 |
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| Greater Than | *e1* `>` *e2* | none | Arithmetic/lexicographic comparison. | 10 |
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| Greater Than or Equal To | *e1* `>=` *e2* | none | Arithmetic/lexicographic 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* <code>||</code> *e2* | left | Logical OR. | 13 |
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| Logical Implication | *e1* `->` *e2* | none | Logical implication (equivalent to <code>!e1 || e2</code>). | 14 |
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