2010/7/25 Andrew Coppin
Patrick Browne wrote:
Andrew, Thanks for your detailed feedback, it is a great help.
Well, I like to be helpful.
I appreciate that the code does not do anything useful, nor is it an appropriate way to write Haskell, but it does help me understand language constructs.
Personally, I find it easier to understand things when they do something meaningful, but sure.
I am studying the Haskell type class system as part of a language comparison. I am trying to exercise and understand the constructs rather than develop a meaningful application.
The best way to understand Haskell is... to completely forget everything you already know, and start again from scratch. ;-) Still, I gather that's not the point of this particular exercise.
Since you're interested in comparisons... A method is simply a way of giving the same name to several different functions, and have the compiler pick the correct one based on the argument types. [snip]
Actually in Haskell, the choice of the correct definition is not only based on the argument types. It could be based on the result type: class C a where f :: a g :: a -> Int h :: String -> a An example of the 'h' case is simply the 'read' function: Prelude> :t read read :: (Read a) => String -> a For instance: Prelude> read "1" :: Int 1 Prelude> read "1" :: Double 1.0 Note that usually, the type annotation is not needed because the compiler has enough information from the context to infer it. Cheers, Thu