ちょっとオブジェクト指向っぽいDSL

Dog.hs

newDog name message
    | message == "bark" = "Bowwow!"
    | message == "hey " ++ name = name ++ " came at you."
    | otherwise = "?"

dog = newDog "Pochi"

main = mapM_ print [dog "bark", dog "hey Pochi", dog "hey John", dog "run"]
{-
output:
"Bowwow!"
"Pochi came at you."
"?"
"?"
-}