Unsure<T> Enum

Unsure<T> is a custom enum which is essentially Option<T> with an additional Reject variant, for handling values that are deemed to be wholly negative (such as a failure state or an invalid input).

Implementation Details

Derived Traits

• Debug: Allows Unsure<T> values to be formatted for debugging purposes.
• Clone: Allows Unsure<T> values to be explicitly cloned with .clone()
• Copy: Allows Unsure<T> values to be copied implicitly, allowing duplication without .clone().
• PartialEq: Allows Unsure<T> values to be compared for equality.
• Eq: Allows Unsure<T> values to be compared for total equality.
• Hash: Allows Unsure<T> values to be used as keys in HashMap or HashSet.
• PartialOrd: Allows Unsure<T> values to be compared for partial ordering.
• Ord: Allows Unsure<T> values to be compared for total ordering.

Variants

• Reject: An erroneous or unwanted value, used to mark a situation where an unsure state should be rejected or cancelled. This is the main reason for using Unsure<T> over Option<T> - if you don't need to manage failure separately from absence, just stick with Option<T>.
• Nothing: No value, like Option<T>'s None, used to mark a situation where an unsure state should be ignored or skipped. Takes its name after Haskell's Nothing variant of the Maybe type.
• Just(T): Some value of type T, like Option<T>'s Some(T), used to confirm that an unsure state is valid and confirmed. Takes its name after Haskell's Just a variant of the Maybe type.

Methods

• is_reject(&self) -> bool: Returns true if the value is Reject, false otherwise.
• is_nothing(&self) -> bool: Returns true if the value is Nothing, false otherwise.
• is_just(&self) -> bool: Returns true if the value is Just(T), false otherwise.
• as_ref(&self) -> Option<&T>: Returns a reference to the value as Some(&T) if it is Just(T), None otherwise.
• as_mut(&mut self) -> Option<&mut T>: Returns a mutable reference to the value as Some(&mut T) if it is Just(T), None otherwise.
• unwrap(self) -> T: Returns the value as T if it is Just(T), panics otherwise.
• unwrap_or(self, default: T) -> T: Returns the value as T if it is Just(T), otherwise returns default.
• unwrap_or_else(self, f: impl FnOnce() -> T) -> T: Returns the value as T if it is Just(T), otherwise calls f and returns the result.
• unwrap_or_default(self) -> T: Returns the value as T if it is Just(T), returns the default if it is Nothing, panics if it is Reject.

From

• From<Option<T>>: Converts an Option<T> to an Unsure<T>. Some(T) maps onto Just(T), None maps onto Nothing. It is impossible to obtain a Reject from this conversion.

Installation

unsure-rs (unsure on crates.io) is a library crate, so you must add it to an existing Rust project:

cargo add unsure

You can additionally type it out manually in Cargo.toml, but using the CLI is easier.

Usage

See the docs.rs for usage instructions and detailed explanations of the enum.