File: existential-any.md

package info (click to toggle)
swiftlang 6.2.3-1
  • links: PTS, VCS
  • area: main
  • in suites: forky, sid
  • size: 2,856,264 kB
  • sloc: cpp: 9,995,718; ansic: 2,234,019; asm: 1,092,167; python: 313,940; objc: 82,726; f90: 80,126; lisp: 38,373; pascal: 25,580; sh: 20,378; ml: 5,058; perl: 4,751; makefile: 4,725; awk: 3,535; javascript: 3,018; xml: 918; fortran: 664; cs: 573; ruby: 396
file content (24 lines) | stat: -rw-r--r-- 891 bytes parent folder | download 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
 
# `ExistentialAny`

This diagnostic group includes errors and warnings pertaining to the `any` type
syntax proposed in [SE-0335].
`any` syntax draws a line between constraint types and existential or boxed
types.

For example, `any Collection` is a boxed type abstracting over a value of a
dynamic type that conforms to the protocol `Collection`, whereas the
`Collection` part is the conformance constraint imposed on the type of the
underlying value *as well as* a constraint type.
The distinction between a conformance constraint and a constraint type can be
clearly seen in classic generic syntax: `<T: Collection>`.

Constraint types exist to express conformances and have no meaning in relation
to values.

```swift
func sillyFunction(collection: Collection) { // error
  // ...
}
```

[SE-0335]: https://github.com/swiftlang/swift-evolution/blob/main/proposals/0335-existential-any.md