Of functions that return Result type and null-safety operators may change their semantics when used The rationale behind these limitations was that future versions of Kotlin might wish to expand and/or change semantics * Do something that produces T or fails */ We'd like to be able to have only a single function with 'success or failure' union type as its parameter: That should get invoked on the successful or failed execution of an asynchronous operation. The primary driver for inclusion of this class into the Standard Library is Continuation callback interface Use cases below on how Result is designed to be used. This restriction was lifted in Kotlin 1.5. NOTE: In Kotlin 1.3 till 1.5 this Result could not be used directly as a return type of Kotlin functions. Where Success T represents a successful result of some type TĪnd Failure Throwable represents a failure with any Throwable exception.įor the purpose of efficiency, we would model it as a generic value class Result We'd like to introduce a type in the Kotlin standard library that is effectively a discriminated union between successfulĪnd failed outcome of execution of Kotlin function - Success T | Failure Throwable,

However, sequential nature of exceptionsĬomplicates their use in cases where some kind of parallel decomposition of work is needed or multipleįailures need to be retained for later processing. Stops further progress and is propagated up to the caller. Exceptions ensure that the first failure in a sequentially performed work Of work in being sequentially decomposed.

Great in any kind of sequential code, including code for a single coroutine or in other case where one piece Exceptions are sequential in nature and work Kotlin provides exceptions that are used to represent an arbitrary failure of a function and includeĪbility to attach additional information pertaining to this failure.

Revisions: Updated in Kotlin 1.5, see revision history.

Contributors: Andrey Breslav, Ilya Gorbunov.Encapsulate successful or failed function execution

Internal fun kotlin