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# Result Builder Methods
To be useful as a result builder, a result builder type must provide a
sufficient subset of function-building methods that enable the transformation of
various statement kinds (`if`, `switch`, `for`..`in`, etc.). The following
example result builder illustrates the various function-building methods one
can define:
```swift
@resultBuilder
struct ExampleResultBuilder {
/// The type of individual statement expressions in the transformed function,
/// which defaults to Component if buildExpression() is not provided.
typealias Expression = ...
/// The type of a partial result, which will be carried through all of the
/// build functions.
typealias Component = ...
/// The type of the final returned result, which defaults to Component if
/// buildFinalResult() is not provided.
typealias Result = ...
/// Required by every result builder to build combined results from
/// statement blocks.
static func buildBlock(_ components: Component...) -> Component { ... }
/// If declared, provides contextual type information for statement
/// expressions to translate them into partial results.
static func buildExpression(_ expression: Expression) -> Component { ... }
/// Enables support for `if` statements that do not have an `else`.
static func buildOptional(_ component: Component?) -> Component { ... }
/// With buildEither(second:), enables support for 'if-else' and 'switch'
/// statements by folding conditional results into a single result.
static func buildEither(first component: Component) -> Component { ... }
/// With buildEither(first:), enables support for 'if-else' and 'switch'
/// statements by folding conditional results into a single result.
static func buildEither(second component: Component) -> Component { ... }
/// Enables support for..in loops in a result builder by combining the
/// results of all iterations into a single result.
static func buildArray(_ components: [Component]) -> Component { ... }
/// If declared, this will be called on the partial result of an 'if
/// #available' block to allow the result builder to erase type
/// information.
static func buildLimitedAvailability(_ component: Component) -> Component { ... }
/// If declared, this will be called on the partial result from the outermost
/// block statement to produce the final returned result.
static func buildFinalResult(_ component: Component) -> Result { ... }
}
```
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