combinando StateT con InputT
Es un seguimiento deesta pregunta. Estoy tratando de combinarshell
de @ ErikR'sresponder en miInputT
lazo.
main :: IO [String]
main = do
c <- makeCounter
execStateT (repl c) []
repl :: Counter -> StateT [String] IO ()
repl c = lift $ runInputT defaultSettings loop
where
loop = do
minput <- getLineIO $ in_ps1 $ c
case minput of
Nothing -> lift $ outputStrLn "Goodbye."
Just input -> (liftIO $ process c input) >> loop
getLineIO :: (MonadException m) => IO String -> InputT m (Maybe String)
getLineIO ios = do
s <- liftIO ios
getInputLine s
Y obteniendo un error
Main.hs:59:10:
Couldn't match type ‘InputT m0’ with ‘IO’
Expected type: StateT [String] IO ()
Actual type: StateT [String] (InputT m0) ()
Relevant bindings include
loop :: InputT (InputT m0) () (bound at Main.hs:61:3)
In the expression: lift $ runInputT defaultSettings loop
In an equation for ‘repl’:
repl c
= lift $ runInputT defaultSettings loop
where
loop
= do { minput <- getLineIO $ in_ps1 $ c;
.... }
Main.hs:62:5:
No instance for (Monad m0) arising from a do statement
The type variable ‘m0’ is ambiguous
Relevant bindings include
loop :: InputT (InputT m0) () (bound at Main.hs:61:3)
Note: there are several potential instances:
instance Monad (Text.Parsec.Prim.ParsecT s u m)
-- Defined in ‘Text.Parsec.Prim’
instance Monad (Either e) -- Defined in ‘Data.Either’
instance Monad Data.Proxy.Proxy -- Defined in ‘Data.Proxy’
...plus 15 others
In a stmt of a 'do' block: minput <- getLineIO $ in_ps1 $ c
In the expression:
do { minput <- getLineIO $ in_ps1 $ c;
case minput of {
Nothing -> lift $ outputStrLn "Goodbye."
Just input -> (liftIO $ process c input) >> loop } }
In an equation for ‘loop’:
loop
= do { minput <- getLineIO $ in_ps1 $ c;
case minput of {
Nothing -> lift $ outputStrLn "Goodbye."
Just input -> (liftIO $ process c input) >> loop } }
El código completo se puede encontraraquí, se basa enEscribirte un haskell.
Lo séhaskelline
tiene un soporte incorporado para la historia, pero estoy tratando de implementarlo yo mismo como ejercicio.
No dude en sugerir reemplazos para los transformadores de mónada para obtener la misma funcionalidad.
Mi verdadero problema
Me gustaria agregaripython
capacidades similares al lambda REPL en Write You a Haskell, a saber:
I. Un contador para entrada y salida, que aparecerá en la solicitud, es decir
In[1]>
Out[1]>
Esto ya eshecho.
II Guarde cada comando en el historial (automáticamente) y muestre todos los comandos anteriores utilizando un comando especial, p.histInput
(igual quehist
enipython
) Además, guarde un historial de todos los resultados de salida y muéstrelos usandohistOutput
. Esto es lo que estoy tratando de hacer en esta pregunta (historial de entrada solo por el momento).
III. Hacer referencia a entradas y salidas anteriores, p. SiIn[1]
estabax
, luegoIn[1] + 2
debe ser sustituido porx + 2
, y del mismo modo para la salida.
Actualizar
He intentado combinar @ ErikR'srespondery deshabilitado temporalmenteshowStep
, dar con:
module Main where
import Syntax
import Parser
import Eval
import Pretty
import Counter
import Control.Monad
import Control.Monad.Trans
import System.Console.Haskeline
import Control.Monad.State
showStep :: (Int, Expr) -> IO ()
showStep (d, x) = putStrLn ((replicate d ' ') ++ "=> " ++ ppexpr x)
process :: Counter -> String -> InputT (StateT [String] IO) ()
process c line =
if ((length line) > 0)
then
if (head line) /= '%'
then do
modify (++ [line])
let res = parseExpr line
case res of
Left err -> outputStrLn $ show err
Right ex -> do
let (out, ~steps) = runEval ex
--mapM_ showStep steps
out_ps1 c $ out2iout $ show out
else do
let iout = handle_cmd line
out_ps1 c iout
-- TODO: don't increment counter for empty lines
else do
outputStrLn ""
out2iout :: String -> IO String
out2iout s = return s
out_ps1 :: Counter -> IO String -> InputT (StateT [String] IO) ()
out_ps1 c iout = do
out <- liftIO iout
let out_count = c 0
outputStrLn $ "Out[" ++ (show out_count) ++ "]: " ++ out
outputStrLn ""
handle_cmd :: String -> IO String
handle_cmd line = if line == "%hist"
then
evalStateT getHist []
else
return "unknown cmd"
getHist :: StateT [String] IO String
getHist = do
hist <- lift get
forM_ (zip [(1::Int)..] hist) $ \(i, h) -> do
show i ++ ": " ++ show h
main :: IO ()
main = do
c <- makeCounter
repl c
repl :: Counter -> IO ()
repl c = evalStateT (runInputT defaultSettings(loop c)) []
loop :: Counter -> InputT (StateT [String] IO) ()
loop c = do
minput <- getLineIO $ in_ps1 $ c
case minput of
Nothing -> return ()
Just input -> process c input >> loop c
getLineIO :: (MonadException m) => IO String -> InputT m (Maybe String)
getLineIO ios = do
s <- liftIO ios
getInputLine s
in_ps1 :: Counter -> IO String
in_ps1 c = do
let ion = c 1
n <- ion
let s = "Untyped: In[" ++ (show n) ++ "]> "
return s
que aún no se compila:
Main.hs:59:5:
Couldn't match type ‘[]’ with ‘StateT [String] IO’
Expected type: StateT [String] IO String
Actual type: [()]
In a stmt of a 'do' block:
forM_ (zip [(1 :: Int) .. ] hist)
$ \ (i, h) -> do { show i ++ ": " ++ show h }
In the expression:
do { hist <- lift get;
forM_ (zip [(1 :: Int) .. ] hist) $ \ (i, h) -> do { ... } }
In an equation for ‘getHist’:
getHist
= do { hist <- lift get;
forM_ (zip [(1 :: Int) .. ] hist) $ \ (i, h) -> ... }