I am trying to invent an embeeded language for measurement instruments. To
do this, I modeled an instrument after the robot language in The Haskell
School of Expression.
For my instrument:
newtype Vi a = Vi (ViState -> (ViState, a))
I have defined:
(||*) :: Vi Bool -> Vi Bool -> Vi Bool
b1 ||* b2 = do
p <- b1
if p then return True else b2
However, I also need to create another instrument:
newtype Dvm a = Dvm (DvmState -> (DvmState, a))
I would like to use the (||*) operator for both Dvm and Vi:
vi ||* dvm
In other words, I need to make logical expressions using two different
monads. How do I write the definition of (||*) to take different monads?
Should I make a new class from Monad, say InstrumentMonad, define my state
monads with it, then write:
(||*) :: (InstrumentMonad a) => a Bool -> a Bool -> a Bool
b1 ||* b2 = do
p <- b1
if p then return True else b2
Mike
