On Tue, Jun 7, 2011 at 10:32 PM, Evan Laforge <[email protected]> wrote:
> > Is this badly designed code that tries to mimic OO in a functional
> setting?
> > If the answer is yes, how could I achieve same result (eg. testing the
> code
> > that does command REPL) without defining type classes?
>
> Here's how I do it:
>
> data InteractiveState = InteractiveState {
> state_read :: IO Command
> , state_write :: Result -> IO ()
> }
>
>
How about :
> data InteractiveState io = InteractiveState {
> state_read :: io Command
> , state_write :: Result -> io ()
> }
Then you don't even depend on some specific monad. I understand you can
always (always?) encapsulate what is done through a type class by using a
data containing functions. But then, is this not even closer to OO
programming, an object that carries its own methods with itself, possibly
with the additional overhead that *each* instance would have its own private
references to possibly identical functions.
Thanks,
Arnaud
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