-- | Pointfree programming fun
--
-- A catalogue of refactorings is at:
--      http://www.cs.kent.ac.uk/projects/refactor-fp/catalogue/
--      http://www.cs.kent.ac.uk/projects/refactor-fp/catalogue/RefacIdeasAug03.html
--
-- Use more Arrow stuff
--
-- TODO would be to plug into HaRe and use some of their refactorings.
module Lambdabot.Plugin.Haskell.Pl (plPlugin) where

import Lambdabot.Plugin
import Lambdabot.Util

import Lambdabot.Plugin.Haskell.Pl.Common          (TopLevel, mapTopLevel, getExpr)
import Lambdabot.Plugin.Haskell.Pl.Parser          (parsePF)
import Lambdabot.Plugin.Haskell.Pl.PrettyPrinter   (Expr)
import Lambdabot.Plugin.Haskell.Pl.Transform       (transform)
import Lambdabot.Plugin.Haskell.Pl.Optimize        (optimize)

import Data.IORef
import System.Timeout

-- firstTimeout is the timeout when the expression is simplified for the first
-- time. After each unsuccessful attempt, this number is doubled until it hits
-- maxTimeout.
firstTimeout, maxTimeout :: Int
firstTimeout :: Int
firstTimeout =  Int
3000000 --  3 seconds
maxTimeout :: Int
maxTimeout   = Int
15000000 -- 15 seconds

type PlState = GlobalPrivate () (Int, TopLevel)
type Pl = ModuleT PlState LB

plPlugin :: Module (GlobalPrivate () (Int, TopLevel))
plPlugin :: Module (GlobalPrivate () (Int, TopLevel))
plPlugin = forall st. Module st
newModule
    { moduleDefState :: LB (GlobalPrivate () (Int, TopLevel))
moduleDefState = forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ forall g p. Int -> g -> GlobalPrivate g p
mkGlobalPrivate Int
15 ()

    , moduleCmds :: ModuleT (GlobalPrivate () (Int, TopLevel)) LB [Command Pl]
moduleCmds = forall (m :: * -> *) a. Monad m => a -> m a
return
        [ (String -> Command Identity
command String
"pointless")
            { aliases :: [String]
aliases = [String
"pl"]
            , help :: Cmd Pl ()
help = forall (m :: * -> *). Monad m => String -> Cmd m ()
say String
"pointless <expr>. Play with pointfree code."
            , process :: String -> Cmd Pl ()
process = String -> Cmd Pl ()
pf
            }
        , (String -> Command Identity
command String
"pl-resume")
            { help :: Cmd Pl ()
help = forall (m :: * -> *). Monad m => String -> Cmd m ()
say String
"pl-resume. Resume a suspended pointless transformation."
            , process :: String -> Cmd Pl ()
process = forall a b. a -> b -> a
const Cmd Pl ()
res
            }
        ]
    }

------------------------------------------------------------------------

res :: Cmd Pl ()
res :: Cmd Pl ()
res = do
  Maybe (Int, TopLevel)
d <- forall (m :: * -> *) g p.
(MonadLBState m, LBState m ~ GlobalPrivate g p) =>
Nick -> m (Maybe p)
readPS forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
=<< forall (m :: * -> *). Monad m => Cmd m Nick
getTarget
  case Maybe (Int, TopLevel)
d of
    Just (Int, TopLevel)
d' -> (Int, TopLevel) -> Cmd Pl ()
optimizeTopLevel (Int, TopLevel)
d'
    Maybe (Int, TopLevel)
Nothing -> forall (m :: * -> *). Monad m => String -> Cmd m ()
say String
"pointless: sorry, nothing to resume."

-- | Convert a string to pointfree form
pf :: String -> Cmd Pl ()
pf :: String -> Cmd Pl ()
pf String
inp = do
    case String -> Either String TopLevel
parsePF String
inp of
        Right TopLevel
d  -> (Int, TopLevel) -> Cmd Pl ()
optimizeTopLevel (Int
firstTimeout, (Expr -> Expr) -> TopLevel -> TopLevel
mapTopLevel Expr -> Expr
transform TopLevel
d)
        Left String
err -> forall (m :: * -> *). Monad m => String -> Cmd m ()
say String
err

optimizeTopLevel :: (Int, TopLevel) -> Cmd Pl ()
optimizeTopLevel :: (Int, TopLevel) -> Cmd Pl ()
optimizeTopLevel (Int
to, TopLevel
d) = do
    Nick
target <- forall (m :: * -> *). Monad m => Cmd m Nick
getTarget
    let (Expr
e,Expr -> TopLevel
decl) = TopLevel -> (Expr, Expr -> TopLevel)
getExpr TopLevel
d
    (Expr
e', Bool
finished) <- forall (m :: * -> *) a. MonadIO m => IO a -> m a
io forall a b. (a -> b) -> a -> b
$ Int -> Expr -> IO (Expr, Bool)
optimizeIO Int
to Expr
e
    let eDecl :: TopLevel
eDecl = Expr -> TopLevel
decl Expr
e'
    forall (m :: * -> *). Monad m => String -> Cmd m ()
say (forall a. Show a => a -> String
show TopLevel
eDecl)
    if Bool
finished
        then forall (m :: * -> *) g p.
(MonadLBState m, LBState m ~ GlobalPrivate g p) =>
Nick -> Maybe p -> m ()
writePS Nick
target forall a. Maybe a
Nothing
        else do
            forall (m :: * -> *) g p.
(MonadLBState m, LBState m ~ GlobalPrivate g p) =>
Nick -> Maybe p -> m ()
writePS Nick
target forall a b. (a -> b) -> a -> b
$ forall a. a -> Maybe a
Just (forall a. Ord a => a -> a -> a
min (Int
2forall a. Num a => a -> a -> a
*Int
to) Int
maxTimeout, TopLevel
eDecl)
            forall (m :: * -> *). Monad m => String -> Cmd m ()
say String
"optimization suspended, use @pl-resume to continue."

------------------------------------------------------------------------

optimizeIO :: Int -> Expr -> IO (Expr, Bool)
optimizeIO :: Int -> Expr -> IO (Expr, Bool)
optimizeIO Int
to Expr
e = do
  IORef Expr
best <- forall a. a -> IO (IORef a)
newIORef Expr
e
  Maybe ()
result <- forall a. Int -> IO a -> IO (Maybe a)
timeout Int
to (forall (t :: * -> *) (m :: * -> *) a b.
(Foldable t, Monad m) =>
(a -> m b) -> t a -> m ()
mapM_ (forall a. IORef a -> a -> IO ()
writeIORef IORef Expr
best forall a b. (a -> b) -> a -> b
$!) forall a b. (a -> b) -> a -> b
$ Expr -> [Expr]
optimize Expr
e)
  Expr
e' <- forall a. IORef a -> IO a
readIORef IORef Expr
best
  forall (m :: * -> *) a. Monad m => a -> m a
return forall a b. (a -> b) -> a -> b
$ case Maybe ()
result of
    Maybe ()
Nothing -> (Expr
e', Bool
False)
    Just ()
_  -> (Expr
e', Bool
True)