On 15/12/2015 15:33, Joachim Durchholz wrote:
I see Kim-Ee Yeoh stating that Martin is stuck without a way forward due to using OO style, which seems more serious than just "wordy and unnatural". Or am I misreading his words, and that "OO-style" reference was just descriptive rather than presenting the base cause of Martin's problems?
The OP originally wrote an insert function with this type: insert :: a -> Maybe (C a) which sort of looks like an insert function from an OO language where the self object is implicit. In functional style it should be insert :: a -> C a -> Maybe (C a) Another way: it's impossible to implement insert :: a -> Maybe (C a) insert a = ??? because there is no 'C a' to modify. -- Carlo Hamalainen http://carlo-hamalainen.net