This is a library that implements a labelled transition system that can be either deterministic or non-deterministic.
Here is an example to use LTS library:
import Data.LTS
main = do
let s0 :: LTSState Int = LTSState {stateId=0, out=3}
let s1 :: LTSState Int = LTSState {stateId=1, out=5}
let s2 :: LTSState Int = LTSState {stateId=2, out=7}
let t1 :: Transition Int Char = Transition {transitionFrom=s0, transitionGuard='a', transitionTo=s1}
let t2 :: Transition Int Char = Transition {transitionFrom=s1, transitionGuard='b', transitionTo=s2}
putStrLn "depth of LTS [t1, t2]:"
print (depth [t1, t2] s0)