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lix/doc/manual/src/language/operators.md

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Pandoc conversion
2020-07-22 21:17:48 +00:00
# Operators
manual: remove "Writing Nix Expressions" chapter it is out of date, all over the place in level of detail, is really about `nixpkgs`, and in general instructions should not be part of a reference manual.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
2022-08-04 09:36:32 +00:00
The table below lists the operators in the Nix language, in
Fix some dangling references
2020-07-24 12:31:33 +00:00
order of precedence (from strongest to weakest binding).
Pandoc conversion
2020-07-22 21:17:48 +00:00
<replaceable> -> <emphasis> Pandoc doesn't know <replaceable> so let's force it to be rendered as italics.
2020-07-23 12:28:05 +00:00
| 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 |
Make lists be comparable Makes lists comparable using lexicographic comparison. Increments builtins.langVersion in order for this change to be detectable
2021-11-22 22:56:40 +00:00
| 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 |
<replaceable> -> <emphasis> Pandoc doesn't know <replaceable> so let's force it to be rendered as italics.
2020-07-23 12:28:05 +00:00
| Equality | *e1* `==` *e2* | none | Equality. | 11 |
| Inequality | *e1* `!=` *e2* | none | Inequality. | 11 |
| Logical AND | *e1* `&&` *e2* | left | Logical AND. | 12 |
doc: Fix escape for operator "logical or" See https://matrix.to/#/!KqkRjyTEzAGRiZFBYT:nixos.org/$hhMb6AdRIXfRkv_LsNsiQJuch7AQ_b6szr4tfawFy-4
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| Logical OR | *e1* <code>&#124;&#124;</code> *e2* | left | Logical OR. | 13 |
| Logical Implication | *e1* `->` *e2* | none | Logical implication (equivalent to <code>!e1 &#124;&#124; e2</code>). | 14 |
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