Performance-loss of accessing data through class?
simons at cryp.to
Sat Oct 9 21:00:54 EDT 2004
in a module I am writing, I am using a 'StateT st IO' monad
with a state like this:
data MyState st = ST !Int !st
My own monad is yet-another wrapper for ... another state
monad. And that's getting inconvenient.
So I wondered whether it would be good to define a class
that unified all those StateTs into _one_ state, like:
> class KnowsMyStuff a where
> foo :: a -> Int
> bar :: a -> Float
> etc :: a -> [String]
Then I could write my functions so that they'd work on any
MonadIO which has some way of getting those instances
If I did that, how much performance would I lose? Accessing
those values would probably require one more level of
indirection, that can't be as fast as having a specific data
Or is there some optimizer magic at work here?
P. S.: Right now the code is _very_ fast, and I'd rather
have that than an convenient interface, that's why I ask.
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