Common Option Methods

• expect(msg: &str) → T: Returns value if Some, panics with custom message if None

Panics. Returning T instead of Option<T>

• unwrap() → T: Returns value if Some, panics if None
• unwrap_or(T) → T: Returns value if Some, otherwise default value
• unwrap_or_else(() → T) → T: Like unwrap_or, but with closure
• unwrap_or_default() → T: Returns value if Some, otherwise default value for type T (requires Default trait)

Modify Option<T>. Closure returns U

• map(T → U) → Option<U>: Transforms Some(T) to Some(U) with closure, None stays None
• map_or(U, T → U) → U: Applies closure to Some(T) to get U, or returns default U if None
• map_or_else(() → U, T → U) → U: Applies closure G to Some(T) to get U, or closure F to get U if None

Modify Option<T>. Closure returns Option

• and_then(T → Option<U>) → Option<U>: Chains operation, applying closure to Some(T) to produce another Option
• filter(&T → bool) → Option<T>: Returns Some(T) if closure returns true, otherwise None
• flatten() → Option<U>: Flattens Option<Option<U>> into Option<U>
• or_else(() → Option<T>) → Option<T>: Returns Some if present, otherwise applies closure

Convert Option<T> to Result<T, E> using:

• ok_or(E) → Result<T, E>: Returns Ok(T) if Some, otherwise Err(E) with provided error.
• ok_or_else(() → E) → Result<T, E>: Like ok_or, but error is computed by closure if None.

Combine

• and(Option<U>) → Option<U>: Returns input Option if both are Some, otherwise None
• or(Option<T>) → Option<T>: Returns first Some, otherwise last None

Check

• is_some() → bool: Returns true if Some, otherwise false
• is_none() → bool: Returns true if None, otherwise false
• contains(U) → bool: Returns true if Some and value equals U, otherwise false