data Task = Task { title :: String, completed :: Bool, subtasks :: [Task] } But that's not really right, because obviously, some tasks don't have
As Jake said - that's fine and you can still pattern match on the null ([]) taskes when looking for tasks without subtaskes.
data Task = Task { title :: String, completed :: Bool } | TaskWithSubtasks { title :: String, completed :: Bool, subtasks :: [Task] } It's a bit more accurate, but it's repeating things, which is ok with a simple type. Could anyone suggest a better way to define this? If I was using C#, which I'm far more familiar with, I could overload the constructor and refer to the smaller constructor.
So do you want: data Job = Job {title :: String, completed :: Bool } data Task = Task Job | MasterTask String [Job] Tom