Targets · Swift · Reserved words

Reserved words

Swift keeps a set of words for its own syntax, so a program cannot use them as names. When a Program name collides with one, the renderer appends a single underscore — class becomes class_ — so the program keeps the name it chose and the output still compiles. Because _ is illegal in a Program identifier, the escape can never collide with a name a program actually chose.

How a Program becomes Swift, in parts. Start with the introduction, then follow each part into the rendered output and the runtime it links against.

Introduction — what the Swift target is, and how to read the rest of this section.
Capabilities — which high-level features are possible, built in or through a library.
Example — a full program using every keyword, and the Swift it renders to.
Naming considerations — how Program's dotted names are carried into Swift.
Entry point — starting a program and mounting it as a SwiftUI app.
Drivers — the native drivers that provide the interface, animation and network.
Runtime — the Reactive and Context machinery the rendered code links against.
Native modules — the hand-written Swift behind NATIVE functions.
Keywords — how each of Program's keywords renders to Swift.
Project setup — the files and commands to build and run the rendered program.
Reserved words — the words Swift keeps for itself, and how a colliding name is escaped.

The full list

Every word Swift reserves, with the identifier a colliding Program name is escaped to. The rule is uniform — append a single _:

Reserved word	Rendered identifier
`associatedtype`	`associatedtype_`
`class`	`class_`
`deinit`	`deinit_`
`enum`	`enum_`
`extension`	`extension_`
`fileprivate`	`fileprivate_`
`func`	`func_`
`import`	`import_`
`init`	`init_`
`inout`	`inout_`
`internal`	`internal_`
`let`	`let_`
`open`	`open_`
`operator`	`operator_`
`private`	`private_`
`protocol`	`protocol_`
`public`	`public_`
`rethrows`	`rethrows_`
`static`	`static_`
`struct`	`struct_`
`subscript`	`subscript_`
`typealias`	`typealias_`
`var`	`var_`
`break`	`break_`
`case`	`case_`
`continue`	`continue_`
`default`	`default_`
`defer`	`defer_`
`do`	`do_`
`else`	`else_`
`fallthrough`	`fallthrough_`
`for`	`for_`
`guard`	`guard_`
`if`	`if_`
`in`	`in_`
`repeat`	`repeat_`
`return`	`return_`
`switch`	`switch_`
`where`	`where_`
`while`	`while_`
`as`	`as_`
`catch`	`catch_`
`false`	`false_`
`is`	`is_`
`nil`	`nil_`
`self`	`self_`
`Self`	`Self_`
`super`	`super_`
`throw`	`throw_`
`throws`	`throws_`
`true`	`true_`
`try`	`try_`
`Any`	`Any_`

Reserved words

Contents

The full list