Fail
Fail is an API operation or result that explicitly records the unsuccessful outcome of a computation, test, parse, or requirement.
Learn Haskell by Example
Fail is an Attoparsec Result constructor representing a failed parse together with remaining input and error information.
- How it is used
- Represents a completed Attoparsec parse failure while preserving remaining input and error information.
- How deep it goes
- Defines Fail and contrasts it with Done and Partial, but defers detailed error handling and focuses on whole-input parsing.
- Examples
- Uses AP.parse with matching, mismatching, and incomplete inputs such as "Hello", "hello", and "He".
- What you can do after
- Evaluate parser results by distinguishing failure from success and incomplete input.
ASP.NET Core in Action, 3e
Fail is an authorization context operation that records explicit failure of an authorization requirement and its containing policy.
- How it is used
- Overrides successful handlers when a policy must reject an authorization requirement explicitly.
- How deep it goes
- Explains explicit failure, handler interaction, and registration, but does not detail Fail overloads or internal middleware implementation.
- Examples
- Uses a banned-lounge claim and a BannedFromLoungeHandler to demonstrate explicit authorization failure.
- What you can do after
- Apply it via ASP.NET Core authorization handlers to ensure disqualifying claims reject a policy despite other successful handlers.
Related concepts
- MonadFailproduced by · MonadFail is a Haskell type class that defines how pattern-match failure is represented within a monadic computation.
- exceptionproduces · An exception is a runtime signal or object representing an abnormal condition that interrupts ordinary program flow and may be handled or propagated.
- JUnituses · JUnit is a Java testing framework for defining, organizing, and running automated tests.
These guides are generated from the text of Manning books by Manning's knowledge graph and link to the sections they draw on. The full books are available on liveBook and at manning.com.