Common Result Methods

• expect(msg: &str): Like unwrap, but with custom err msg
• expect_none(msg: &str): Panics with custom message if Err, expects None for Option (used with Result<Option<T>, E>)

Panics. Returning T instead of Result<T, E>

• unwrap(): Return value if Ok, otherwise panics
• unwrap_or(T) → T: Return value if Ok, otherwise default value
• unwrap_or_else(() → T) → T: Like unwrap_or, but with closure
• unwrap_or_default() → T: Returns value if Ok, otherwise default value for type T (requires Default trait)

Modify Result<T, E>. Closure returns U

• map(T → U) → Result<U, E>: Transform Ok(T) to Ok(U) with a closure
• map_err(E → U) → Result<T, U>: Transform Err(T) to Err(U) with a closure
• map_or(U, T → U) → U: Applies closure to Ok(T) to get U, or returns default U if Err
• map_or_else(E → U, T → U) → U: Applies closure G to Ok(T) to get U, or closure F to Err(E) to get U

Modify Result<T, E>. Closure returns Result

• and_then(T → Result<U, E>) → Result<U, E>: Chains operation, applying a closure to Ok(T) to produce another Result
• or_else(E → Result<U, E>) → Result<U, E>: Like and_then, but for Err(T)
• flatten() → Result<U, E>: Flattens Result<Result<U, E>, E> into Result<U, E>
• transpose() → Option<Result<T, E>>: Converts Result<Option<T>, E> to Option<Result<T, E>>

Combine

• and(Result<U, E>) → Result<U, E>: Returns input Result if both are Ok, otherwise first Err
• or(Result<T, F>) → Result<T, F>: Returns first Ok, otherwise last Err

Check

• is_ok(): Returns true if Ok, otherwise false
• is_err(): Returns true if Err, otherwise false
• contains(U) → bool: Returns true if Ok and value equals U, otherwise false
• contains_err(U) → bool: Returns true if Err and error equals U, otherwise false