mirror of
https://github.com/idris-lang/Idris2.git
synced 2024-12-15 14:23:32 +03:00
126 lines
3.9 KiB
Idris
126 lines
3.9 KiB
Idris
import Data.String
|
|
|
|
VendState : Type
|
|
VendState = (Nat, Nat)
|
|
|
|
data Input = COIN
|
|
| VEND
|
|
| CHANGE
|
|
| REFILL Nat
|
|
|
|
strToInput : String -> Maybe Input
|
|
strToInput "insert" = Just COIN
|
|
strToInput "vend" = Just VEND
|
|
strToInput "change" = Just CHANGE
|
|
strToInput x = if all isDigit (unpack x)
|
|
then Just (REFILL (stringToNatOrZ x))
|
|
else Nothing
|
|
|
|
export
|
|
data MachineCmd : Type ->
|
|
VendState -> VendState ->
|
|
Type where
|
|
InsertCoin : MachineCmd () (pounds, chocs) (S pounds, chocs)
|
|
Vend : MachineCmd () (S pounds, S chocs) (pounds, chocs)
|
|
GetCoins : MachineCmd () (pounds, chocs) (Z, chocs)
|
|
|
|
Refill : (bars : Nat) ->
|
|
MachineCmd () (Z, chocs) (Z, bars + chocs)
|
|
|
|
Display : String -> MachineCmd () state state
|
|
GetInput : MachineCmd (Maybe Input) state state
|
|
|
|
Pure : ty -> MachineCmd ty state state
|
|
(>>=) : {state2 : _} ->
|
|
MachineCmd a state1 state2 ->
|
|
(a -> MachineCmd b state2 state3) ->
|
|
MachineCmd b state1 state3
|
|
|
|
export
|
|
data MachineIO : VendState -> Type where
|
|
Do : {state1 : _} ->
|
|
MachineCmd a state1 state2 ->
|
|
(a -> Inf (MachineIO state2)) -> MachineIO state1
|
|
|
|
runMachine : {inState : _} -> MachineCmd ty inState outState -> IO ty
|
|
runMachine InsertCoin = putStrLn "Coin inserted"
|
|
runMachine Vend = putStrLn "Please take your chocolate"
|
|
runMachine {inState = (pounds, _)} GetCoins
|
|
= putStrLn (show pounds ++ " coins returned")
|
|
runMachine (Display str) = putStrLn str
|
|
runMachine (Refill bars)
|
|
= putStrLn ("Chocolate remaining: " ++ show bars)
|
|
runMachine {inState = (pounds, chocs)} GetInput
|
|
= do putStrLn ("Coins: " ++ show pounds ++ "; " ++
|
|
"Stock: " ++ show chocs)
|
|
putStr "> "
|
|
x <- getLine
|
|
pure (strToInput x)
|
|
runMachine (Pure x) = pure x
|
|
runMachine (cmd >>= prog) = do x <- runMachine cmd
|
|
runMachine (prog x)
|
|
|
|
namespace MachineDo
|
|
export
|
|
(>>=) : {state1 : _} ->
|
|
MachineCmd a state1 state2 ->
|
|
(a -> Inf (MachineIO state2)) -> MachineIO state1
|
|
(>>=) = Do
|
|
|
|
export
|
|
(>>) : {state1 : _} ->
|
|
MachineCmd a state1 state2 ->
|
|
Inf (MachineIO state2) ->
|
|
MachineIO state1
|
|
ma >> mb = ma >>= const mb
|
|
|
|
|
|
|
|
data Fuel = Dry | More (Lazy Fuel)
|
|
|
|
partial
|
|
forever : Fuel
|
|
forever = More forever
|
|
|
|
ignore : IO a -> IO ()
|
|
ignore mx = do x <- mx; pure ()
|
|
|
|
run : Fuel -> MachineIO mstate -> IO ()
|
|
run (More fuel) (Do c f)
|
|
= do res <- runMachine c
|
|
run fuel (f res)
|
|
run Dry p = pure ()
|
|
|
|
mutual
|
|
vend : {pounds, chocs : _} -> MachineIO (pounds, chocs)
|
|
vend {pounds = (S p)} {chocs = (S c)} = do Vend
|
|
Display "Enjoy!"
|
|
machineLoop
|
|
vend {pounds = Z} = do Display "Insert a coin"
|
|
machineLoop
|
|
vend {chocs = Z} = do Display "Out of stock"
|
|
machineLoop
|
|
|
|
refill: {pounds, chocs : _} -> (num : Nat) -> MachineIO (pounds, chocs)
|
|
refill {pounds = Z} num = do Refill num
|
|
machineLoop
|
|
refill _ = do Display "Can't refill: Coins in machine"
|
|
machineLoop
|
|
|
|
machineLoop : {pounds, chocs : _} -> MachineIO (pounds, chocs)
|
|
machineLoop = -- Do (Display "Foo") (\x => machineLoop)
|
|
do Just x <- GetInput
|
|
| Nothing => do Display "Invalid input"
|
|
machineLoop
|
|
case x of
|
|
COIN => do InsertCoin
|
|
machineLoop
|
|
VEND => vend
|
|
CHANGE => do GetCoins
|
|
Display "Change returned"
|
|
machineLoop
|
|
REFILL num => refill num
|
|
|
|
main : IO ()
|
|
main = run forever (machineLoop {pounds = 0} {chocs = 1})
|