prompt.hs

import Data.Map as Map

type Inventory = [String]

data Direction = North
               | South
               | East
               | West
               | Up
               | Down
               deriving (Eq, Show, Ord)

data Location = Location {
	    exits :: Map Direction Location,
	    description :: String }

instance Show Location where 
    show (Location exits description) = "Sei " ++ description

-- Map definition
cabinaPilotaggio = Location {
    exits = fromList [( South, corridoioPrua )],
    description = "nella cabina di pilotaggio" }

cabinaSecondo = Location {
    exits = fromList [( East, corridoioPrua )],
    description = "nella cabina del secondo pilota" }

cabinaComandante = Location {
    exits = fromList [( East, corridoio )],
    description = "nella cabina del comandante" }

corridoioPrua = Location {
	exits = fromList [( North, cabinaPilotaggio ),
	                  ( South, corridoio ),
	                  ( East, compartimentoPasseggeri ),
	                  ( West, cabinaSecondo ) ],
	description = "ad un'estremità del corridoio" }

corridoioPoppa = Location {
	exits = fromList [( North, corridoio ),
	                  ( East, compartimentoPasseggeri ),
	                  ( West, compartimentoStagno ),
	                  ( South, controlloReattore ) ],
	description = "ad un'estremità del corridoio" }

compartimentoStagno = Location {
	exits = fromList [( West, corridoioPoppa ) ],
	description = "ad un'estremità del corridoio" }

corridoio = Location {
	exits = fromList [( North, corridoioPrua ),
	                  ( South, corridoioPoppa ),
	                  ( East, compartimentoPasseggeri ),
	                  ( West, cabinaComandante ) ],
	description = "nel corridoio" }

compartimentoPasseggeri = Location {
	exits = fromList [( West, corridoio ) ],
	description = "nel compartimento passeggeri" }

controlloReattore = Location {
    exits = fromList [( North, corridoioPoppa )],
    description = "nella salata controllo del reattore" }

type PlayerPosition = Location

go :: Location -> Direction -> Location
go position direction = 
    case newposition of 
        Just value -> value
        Nothing    -> position
    where newposition = Map.lookup direction ( exits position )

describe :: Location -> IO ()
describe position = putStrLn $ show position

data AdventureState = AdventureState {
        playerPosition  :: PlayerPosition, -- Where's the player in the map?
        playerInventory :: Inventory -- What is the player carrying?
    } deriving (Show)

main = do 
    mainLoop (AdventureState corridoioPrua [])

mainLoop :: AdventureState -> IO ()
mainLoop state
    = do 
        describe (playerPosition state)
        putStr "?> "
        inputString <- getLine
        case inputString of
            "N" -> (do 
                mainLoop $ (AdventureState  
                    (go (playerPosition state) North)
                    (playerInventory state) ) ) 
            "S" -> (do 
                mainLoop $ (AdventureState  
                    (go (playerPosition state) South)
                    (playerInventory state) ) ) 
            "W" -> (do 
                mainLoop $ (AdventureState  
                    (go (playerPosition state) West)
                    (playerInventory state) ) ) 
            "E" -> (do 
                mainLoop $ (AdventureState  
                    (go (playerPosition state) East)
                    (playerInventory state) ) ) 
            "quit" -> (do 
                putStrLn "Ciao!")
            _ -> (do 
                putStrLn "Comando non riconosciuto"
                mainLoop state)