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You don't touch on the fact that options act can act Monads (i.e., that you can invoke an operation on the inner value, conditional on whether or not the option
by anorwell 12y ago
You don't touch on the fact that options act can act Monads (i.e., that you can invoke an operation on the inner value, conditional on whether or not the optional value is present). For example, an optional user translates naturally to an optional user.name.
I haven't tried swift, and it's not obvious to me from the swift documentation if their options support arbitrary transformations, or just method chaining. In ruby (with ActiveSupport) this is the difference between:
might_be_nil.try(:method)
and
might_be_nil.try { |value| my_function(value) }
The latter is more general and useful than the former.
- nottombrown 12y agoHere's the source of try from active_support def try(*a, &b) if a.empty? && block_given? yield self else public_send(*a, &b) if respond_to?(a.first) end end https://github.com/rails/rails/blob/d68419a88e424e588c2d8decc69874bd00588766/activesupport/lib/active_support/core_ext/object/try.rb https://github.com/rails/rails/blob/d68419a88e424e588c2d8dec... Should be easy to do the same in swift. Let me take a stab at it.
- nottombrown 12y agoHere's an implementation of the latter try operator in swift. extension Optional { func try<U>(f: (T) -> U) -> Optional<U> { if let unwrapped = self { return f(unwrapped) } else { return nil } } } You can see how to use it in this gist: https://gist.github.com/nottombrown/c6585cad9588a9dc5383 https://gist.github.com/nottombrown/c6585cad9588a9dc5383