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diff --git a/doc/manual/src/expressions/language-operators.md b/doc/manual/src/expressions/language-operators.md new file mode 100644 index 000000000..1d787ffe3 --- /dev/null +++ b/doc/manual/src/expressions/language-operators.md @@ -0,0 +1,29 @@ +# Operators + +The table below lists the operators in the Nix expression 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 comparison. | 10 | +| Less Than or Equal To | *e1* `<=` *e2* | none | Arithmetic comparison. | 10 | +| Greater Than | *e1* `>` *e2* | none | Arithmetic comparison. | 10 | +| Greater Than or Equal To | *e1* `>=` *e2* | none | Arithmetic 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 | |