Do notation provides an alternative to bind, which also flattens the code.

bind applies unwrapped Success value to the block, which should return a Result object. No-op on Failure

To get the final value you can use value_or which is a safe way to unwrap a nil-able value.

can transform monadic values m a applying f to the unwrapped value a

A combinator, typically called bind (as in binding a variable) and represented with an infix operator >>=, that unwraps a monadic variable, then inserts it into a monadic function/expression, resulting in a new monadic value:(mx >>= f) : (M T, T → M U) → M U