bring back table, extract annotations
this makes the table less unwieldy, and leaves enough space for extensive explanations.
This commit is contained in:
Valentin Gagarin
parent
7da59e94ae
commit
e57165b85a
|
|
@ -1,117 +1,96 @@
|
|||
# Operators
|
||||
|
||||
| Name | Syntax | Associativity | Precedence |
|
||||
|----------------------------------------|--------------------------------------------|---------------|------------|
|
||||
| [Attribute selection] | *attrset* `.` *attrpath* \[ `or` *expr* \] | none | 1 |
|
||||
| Function application | *func* *expr* | left | 2 |
|
||||
| [Arithmetic negation][arithmetic] | `-` *number* | none | 3 |
|
||||
| [Has attribute] | *attrset* `?` *attrpath* | none | 4 |
|
||||
| List concatenation | *list* `++` *list* | right | 5 |
|
||||
| [Multiplication][arithmetic] | *number* `*` *number* | left | 6 |
|
||||
| [Division][arithmetic] | *number* `/` *number* | left | 6 |
|
||||
| [Subtraction][arithmetic] | *number* `-` *number* | left | 7 |
|
||||
| [Addition][arithmetic] | *number* `+` *number* | left | 7 |
|
||||
| [String concatenation] | *string* `+` *string* | left | 7 |
|
||||
| [Path concatenation] | *path* `+` *path* | left | 7 |
|
||||
| [Path and string concatenation] | *path* `+` *string* | left | 7 |
|
||||
| [String and path concatenation] | *string* `+` *path* | left | 7 |
|
||||
| Logical negation (`NOT`) | `!` *bool* | none | 8 |
|
||||
| [Update] | *attrset* `//` *attrset* | right | 9 |
|
||||
| [Less than][Comparison] | *expr* `<` *expr* | none | 10 |
|
||||
| [Less than or equal to][Comparison] | *expr* `<=` *expr* | none | 10 |
|
||||
| [Greater than][Comparison] | *expr* `>` *expr* | none | 10 |
|
||||
| [Greater than or equal to][Comparison] | *expr* `>=` *expr* | none | 10 |
|
||||
| [Equality] | *expr* `==` *expr* | none | 11 |
|
||||
| Inequality | *expr* `!=` *expr* | none | 11 |
|
||||
| Logical conjunction (`AND`) | *bool* `&&` *bool* | left | 12 |
|
||||
| Logical disjunction (`OR`) | *bool* `||` *bool* | left | 13 |
|
||||
| [Logical implication] | *bool* `->` *bool* | none | 14 |
|
||||
|
||||
[string]: ./values.md#type-string
|
||||
[path]: ./values.md#type-path
|
||||
[number]: ./values.md#type-number
|
||||
[list]: ./values.md#list
|
||||
[attribute set]: ./values.md#attribute-set
|
||||
|
||||
## Attribute selection
|
||||
|
||||
> *attrset* `.` *attrpath* \[ `or` *value* \]
|
||||
|
||||
Select the attribute denoted by attribute path *attrpath* from [attribute set] *attrset*.
|
||||
An attribute path is a dot-separated list of attribute names.
|
||||
If the attribute doesn’t exist, return *value* if provided, otherwise abort evaluation.
|
||||
|
||||
Associativity: none
|
||||
<!-- FIXME: the following should to into its own language syntax section, but that needs more work to fit in well -->
|
||||
|
||||
Precedence: 1
|
||||
An attribute path is a dot-separated list of attribute names.
|
||||
An attribute name can be an identifier or a string.
|
||||
|
||||
## Function application
|
||||
> *attrpath* = *name* [ `.` *name* ]...
|
||||
> *name* = *identifier* | *string*
|
||||
> *identifier* ~ `[a-zA-Z_][a-zA-Z0-9_'-]*`
|
||||
|
||||
> *f* *a*
|
||||
|
||||
Call [function] *f* with argument *a*.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 2
|
||||
|
||||
## Arithmetic negation
|
||||
|
||||
> `-` *n*
|
||||
|
||||
Flip the sign of the [number] *n*.
|
||||
|
||||
Associativity: none
|
||||
|
||||
Precedence: 3
|
||||
[Attribute selection]: #attribute-selection
|
||||
|
||||
## Has attribute
|
||||
|
||||
> *attrset* `?` *attrpath*
|
||||
|
||||
Test whether [attribute set] *attrset* contains the attribute denoted by *attrpath*; return `true` or `false`.
|
||||
Test whether [attribute set] *attrset* contains the attribute denoted by *attrpath*.
|
||||
The result is a [Boolean] value.
|
||||
|
||||
Associativity: none
|
||||
[Boolean]: ./values.md#type-boolean
|
||||
|
||||
Precedence: 4
|
||||
[Has attribute]: #has-attribute
|
||||
|
||||
## List concatenation
|
||||
## Arithmetic
|
||||
|
||||
> *list1* `++` *list2*
|
||||
Numbers are type-compatible:
|
||||
Pure integer operations will always return integers, whereas any operation involving at least one floating point number return a floating point number.
|
||||
|
||||
Concatenate [list]s *list1* and *list2*.
|
||||
See also [Comparison] and [Equality].
|
||||
|
||||
Associativity: right
|
||||
The `+` operator is overloaded to also work on strings and paths.
|
||||
|
||||
Precedence: 5
|
||||
|
||||
## Multiplication
|
||||
|
||||
> *n1* `*` *n2*,
|
||||
|
||||
Multiply [number]s *n1* and *n2*.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 6
|
||||
|
||||
## Division
|
||||
|
||||
> *n1* `/` *n2*
|
||||
|
||||
Divide [number]s *n1* and *n2*.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 6
|
||||
|
||||
## Subtraction
|
||||
|
||||
> *n1* `-` *n2*
|
||||
|
||||
Subtract [number] *n2* from *n1*.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 7
|
||||
|
||||
## Addition
|
||||
|
||||
> *n1* `+` *n2*
|
||||
|
||||
Add [number]s *n1* and *n2*.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 7
|
||||
[arithmetic]: #arithmetic
|
||||
|
||||
## String concatenation
|
||||
|
||||
> *string1* `+` *string2*
|
||||
> *string* `+` *string*
|
||||
|
||||
Concatenate two [string]s and merge their string contexts.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 7
|
||||
[String concatenation]: #string-concatenation
|
||||
|
||||
## Path concatenation
|
||||
|
||||
> *path1* `+` *path2*
|
||||
> *path* `+` *path*
|
||||
|
||||
Concatenate two [path]s.
|
||||
The result is a path.
|
||||
|
||||
[Path concatenation]: #path-concatenation
|
||||
|
||||
## Path and string concatenation
|
||||
|
||||
> *path* `+` *string*
|
||||
> *path* + *string*
|
||||
|
||||
Concatenate *[path]* with *[string]*.
|
||||
The result is a path.
|
||||
|
|
@ -120,13 +99,11 @@ The result is a path.
|
|||
>
|
||||
> The string must not have a string context that refers to a [store path].
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 7
|
||||
[Path and string concatenation]: #path-and-string-concatenation
|
||||
|
||||
## String and path concatenation
|
||||
|
||||
> *string* `+` *path*
|
||||
> *string* + *path*
|
||||
|
||||
Concatenate *[string]* with *[path]*.
|
||||
The result is a string.
|
||||
|
|
@ -136,123 +113,55 @@ The result is a string.
|
|||
> The file or directory at *path* must exist and is copied to the [store].
|
||||
> The path appears in the result as the corresponding [store path].
|
||||
|
||||
Associativity: left
|
||||
[store path]: ../glossary.md#gloss-store-path
|
||||
[store]: ../glossary.md#gloss-store
|
||||
|
||||
Precedence: 7
|
||||
|
||||
## Logical negation (`NOT`)
|
||||
|
||||
> `!` *b*
|
||||
|
||||
Negate the [Boolean] value *b*.
|
||||
|
||||
Associativity: none
|
||||
|
||||
Precedence: 8
|
||||
[Path and string concatenation]: #path-and-string-concatenation
|
||||
|
||||
## Update
|
||||
|
||||
> *attrset1* `//` *attrset1*
|
||||
> *attrset1* + *attrset2*
|
||||
|
||||
Update [attribute set] *attrset1* with names and values from *attrset2*.
|
||||
|
||||
The returned attribute set will have of all the attributes in *e1* and *e2*.
|
||||
If an attribute name is present in both, the attribute value from the former is taken.
|
||||
|
||||
Associativity: right
|
||||
|
||||
Precedence: 9
|
||||
[Update]: #update
|
||||
|
||||
## Comparison
|
||||
|
||||
- Arithmetic comparison for [number]s
|
||||
- Lexicographic comparison for [string]s and [path]s
|
||||
- Lexicographic comparison for [list]s:
|
||||
Elements at the same index in both lists are compared according to their type and skipped if they are equal.
|
||||
Comparison is
|
||||
|
||||
Associativity: none
|
||||
- [arithmetic] for [number]s
|
||||
- lexicographic for [string]s and [path]s
|
||||
- item-wise lexicographic for [list]s:
|
||||
elements at the same index in both lists are compared according to their type and skipped if they are equal.
|
||||
|
||||
Precedence: 10
|
||||
All comparison operators are implemented in terms of `<`, and the following equivalencies hold:
|
||||
|
||||
### Less than
|
||||
| comparison | implementation |
|
||||
|--------------|-----------------------|
|
||||
| *a* `<=` *b* | `! (` *b* `<` *a* `)` |
|
||||
| *a* `>` *b* | *b* `<` *a* |
|
||||
| *a* `>=` *b* | `! (` *a* `<` *b* `)` |
|
||||
|
||||
> *e1* `<` *e2*,
|
||||
|
||||
### Less than or equal to
|
||||
|
||||
> *e1* `<=` *e2*
|
||||
|
||||
### Greater than
|
||||
|
||||
> *e1* `>` *e2*
|
||||
|
||||
### Greater than or equal to
|
||||
|
||||
> *e1* `>=` *e2*
|
||||
[Comparison]: #comparison-operators
|
||||
|
||||
## Equality
|
||||
|
||||
> *e1* `==` *e2*
|
||||
|
||||
Check expressions *e1* and *e2* for value equality.
|
||||
|
||||
- [Attribute sets][attribute set] and [list]s are compared recursively, and therefore are fully evaluated.
|
||||
- Comparison of [function]s always returns `false`.
|
||||
- Integers are coerced to floating point numbers if compared to floating point numbers.
|
||||
- Numbers are type-compatible, see [arithmetic] operators.
|
||||
- Floating point numbers only differ up to a limited precision.
|
||||
|
||||
Associativity: none
|
||||
[function]: ./constructs.md#functions
|
||||
|
||||
Precedence: 11
|
||||
|
||||
## Inequality
|
||||
|
||||
> *e1* `!=` *e2*
|
||||
|
||||
Equivalent to `! (`*e1* `==` *e2* `)`
|
||||
|
||||
Associativity: none
|
||||
|
||||
Precedence: 11
|
||||
|
||||
## Logical conjunction (`AND`)
|
||||
|
||||
> *b1* `&&` *b2*
|
||||
|
||||
Return `true` if and only if both `b1` and `b2` evaluate to `true`, otherwise `false`.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 12
|
||||
|
||||
## Logical disjunction (`OR`)
|
||||
|
||||
> *b1* `||` *b2*
|
||||
|
||||
Return `true` if at least one of `b1` or `b2` evaluate to `true`, otherwise `false`.
|
||||
|
||||
Associativity: left
|
||||
|
||||
Precedence: 13
|
||||
[Equality]: #equality
|
||||
|
||||
## Logical implication
|
||||
|
||||
> *b1* `->` *b2*
|
||||
|
||||
Return `false` if *b1* evaluates to `true` and *b2* evaluates to `false`, otherwise `true`.
|
||||
|
||||
Equivalent to `!`*b1* `||` *b2*.
|
||||
|
||||
Associativity: none
|
||||
[Logical implication]: #logical-implication
|
||||
|
||||
Precedence: 14
|
||||
|
||||
[string]: ./values.md#type-string
|
||||
[path]: ./values.md#type-path
|
||||
[number]: ./values.md#type-number
|
||||
[Boolean]: ./values.md#type-boolean
|
||||
[list]: ./values.md#list
|
||||
[attribute set]: ./values.md#attribute-set
|
||||
[function]: ./constructs.md#functions
|
||||
[store path]: ../glossary.md#gloss-store-path
|
||||
[store]: ../glossary.md#gloss-store
|
||||
|
|
|
|||
|
|
@ -85,11 +85,10 @@
|
|||
Numbers, which can be *integers* (like `123`) or *floating point*
|
||||
(like `123.43` or `.27e13`).
|
||||
|
||||
Numbers are type-compatible: pure integer operations will always
|
||||
return integers, whereas any operation involving at least one
|
||||
floating point number will have a floating point number as a result.
|
||||
See [arithmetic] and [comparison] operators for semantics.
|
||||
|
||||
Floating point numbers only differ up to a limited precision.
|
||||
[arithmetic]: ./operators.md#arithmetic
|
||||
[comparison]: ./operators.md#comparison
|
||||
|
||||
- <a id="type-path" href="#type-path">Path</a>
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue