My OS is ubuntu. I've used synaptic to install:
hat 2.05 rerolled-5ubuntu1.
The installed files include several in /usr/include/hat-2.05, including
Control/Monad/State.hx. I would like to use hat to trace what
happens with the code:
plus n x
shown here:
http://hackage.haskell.org/packages/archive/mtl/latest/doc/html/Control-Mon…
However, I've tried several variations of the Makefile:
{--cut here--
MAIN=tickSimple
INCS=
GHC.FLAGS=-i$(INCS)
GHC.FLAGS=-XMultiParamTypeClasses -XFunctionalDependencies
-XFlexibleInstances
GHC.PKGS= -package Hat.Control.Monad.State
GHC.PKGS=
GHC.OPTS=$(GHC.FLAGS) $(GHC.PKGS)
hat:
hmake -hat $(GHC.OPTS) $(MAIN)
hat-trans $(GHC.OPTS) $(MAIN).hs
ghc -package hat $(GHC.OPTS) -c Hat/$(MAIN).o Hat/$(MAIN).hs
ghc -package hat $(GHC.OPTS) -o Hat/$(MAIN) Hat/$(MAIN).o
{--cut here--
On the source file:
{--tickSimple.hs--
module Main where
-- newtype State
-- class MonadState
-- instance MonadState (State s)
-- cp'ed from:
--
http://www.haskell.org/all_about_monads/html/statemonad.html#definition
newtype State s a = State { runState :: (s -> (a,s)) }
instance Monad (State s) where
return a = State $ \s -> (a,s)
(State x) >>= f = State $ \s -> let (v,s') = x s in runState (f v) s'
class MonadState m s | m -> s where
get :: m s
put :: s -> m ()
instance MonadState (State s) s where
get = State $ \s -> (s,s)
put s = State $ \_ -> ((),s)
-- execState:
-- just guesses based on:
--
http://hackage.haskell.org/packages/archive/mtl/latest/doc/html/Control-Mon…
execState :: State s a -> s -> a
execState s = snd(runState(s))
tick :: State Int Int
tick = do n <- get
put (n+1)
return n
plusOne :: Int -> Int
plusOne n = execState tick n
plus :: Int -> Int -> Int
plus n x = execState (sequence $ replicate n tick) x
main = do
print (plusOne 2)
print (plus 2 3)
}--tickSimple.hs--
However, I always get some error.
I have tried just using:
import Control.Monad.State
But the compiler then says it can't find the library.
What should I do to debug this code with hat?
TIA
-regards,
Larry
