---
title: Result builder methods (ResultBuilderMethods)
framework: swift-compiler
role: article
role_heading: Article
path: swift-compiler/documentation/diagnostics/result-builder-methods
---

# Result builder methods (ResultBuilderMethods)

## Overview

Overview 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: @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 { ... } }

## See Also

- [@dynamicCallable implementation requirements (DynamicCallable)](swift-compiler/documentation/diagnostics/dynamic-callable-requirements.md)
- [Add @preconcurrency import (AddPreconcurrencyImport)](swift-compiler/documentation/diagnostics/add-preconcurrency-import.md)
- [Always enabled availability domains (AlwaysAvailableDomain)](swift-compiler/documentation/diagnostics/always-available-domain.md)
- [Argument matching for trailing closures (TrailingClosureMatching)](swift-compiler/documentation/diagnostics/trailing-closure-matching.md)
- [Calling a mutating async actor-isolated method (ActorIsolatedMutatingAsync)](swift-compiler/documentation/diagnostics/actor-isolated-mutating-async.md)
- [Calling an actor-isolated method from a synchronous nonisolated context (ActorIsolatedCall)](swift-compiler/documentation/diagnostics/actor-isolated-call.md)
- [Captures in a `@Sendable` closure (SendableClosureCaptures)](swift-compiler/documentation/diagnostics/sendable-closure-captures.md)
- [Compilation caching (CompilationCaching)](swift-compiler/documentation/diagnostics/compilation-caching.md)
- [Conforming to `StringInterpolationProtocol` (StringInterpolationConformance)](swift-compiler/documentation/diagnostics/string-interpolation-conformance.md)
- [Conversion from `@isolated(any)` function type to synchronous function type (ConversionFromIsolatedAnyToSynchronous)](swift-compiler/documentation/diagnostics/conversion-from-isolated-any-to-synchronous.md)
- [Cross-isolation data race (RegionIsolationCrossIsolationDataRace)](swift-compiler/documentation/diagnostics/region-isolation-cross-isolation-data-race.md)
- [Deprecated declaration warnings (DeprecatedDeclaration)](swift-compiler/documentation/diagnostics/deprecated-declaration.md)
- [Deprecated implementation-only imports (ImplementationOnlyDeprecated)](swift-compiler/documentation/diagnostics/implementation-only-deprecated.md)
- [Dynamic exclusivity (DynamicExclusivity)](swift-compiler/documentation/diagnostics/dynamic-exclusivity.md)
- [Embedded Swift language restrictions (EmbeddedRestrictions)](swift-compiler/documentation/diagnostics/embedded-restrictions.md)