Keep only values which satisfy a predicate
Returns the result of applying f to this OptionT if this OptionT is not empty
Returns the result of applying f to this OptionT if this OptionT is not empty
a new OptionT
Returns the result of applying f to this OptionT if this OptionT is not empty
Returns the result of applying f to this OptionT if this OptionT is not empty
a new OptionT
Keep only values which satisfy a predicate