Navigation : Prerequisites Build and install Review of Error Handling Frameworks Motivation Future ABI stability guarantees Tutorial Recipes Experimental API reference - Macros - Concepts - Converters -- `value_or_error<T, U>` - Traits - Policies - Types - Aliases - Functions Frequently asked questions Videos Changelog History Converters value_or_error<T, U> A customisable converter of value_or_error<T, E> concept matching types. value_or_none<T> value_or_error<T, U>