{-# LANGUAGE DoAndIfThenElse, NoOverloadedStrings, TypeSynonymInstances, CPP #-}
{- | Description : Wrapper around GHC API, exposing a single `evaluate` interface that runs
a statement, declaration, import, or directive.
This module exports all functions used for evaluation of IHaskell input.
-}
module IHaskell.Eval.Evaluate (
interpret, evaluate, Interpreter, liftIO, typeCleaner, globalImports
) where
import ClassyPrelude hiding (init, last, liftIO, head, hGetContents, tail, try)
import Control.Concurrent (forkIO, threadDelay)
import Prelude (putChar, head, tail, last, init, (!!))
import Data.List.Utils
import Data.List(findIndex, and)
import Data.String.Utils
import Text.Printf
import Data.Char as Char
import Data.Dynamic
import Data.Typeable
import qualified Data.Serialize as Serialize
import System.Directory
import Filesystem.Path.CurrentOS (encodeString)
import System.Posix.IO
import System.IO (hGetChar, hFlush)
import System.Random (getStdGen, randomRs)
import Unsafe.Coerce
import Control.Monad (guard)
import System.Process
import System.Exit
import Data.Maybe (fromJust)
import qualified Control.Monad.IO.Class as MonadIO (MonadIO, liftIO)
import qualified MonadUtils (MonadIO, liftIO)
import System.Environment (getEnv)
import qualified Data.Map as Map
import NameSet
import Name
import PprTyThing
import InteractiveEval
import DynFlags
import Type
import Exception (gtry)
import HscTypes
import HscMain
import qualified Linker
import TcType
import Unify
import InstEnv
import GhcMonad (liftIO, withSession)
import GHC hiding (Stmt, TypeSig)
import GHC.Paths
import Exception hiding (evaluate)
import Outputable hiding ((<>))
import Packages
import Module
import qualified Pretty
import FastString
import Bag
import ErrUtils (errMsgShortDoc, errMsgExtraInfo)
import qualified System.IO.Strict as StrictIO
import IHaskell.Types
import IHaskell.IPython
import IHaskell.Eval.Parser
import IHaskell.Eval.Lint
import IHaskell.Display
import qualified IHaskell.Eval.Hoogle as Hoogle
import IHaskell.Eval.Util
import IHaskell.BrokenPackages
import qualified IHaskell.IPython.Message.UUID as UUID
import Paths_ihaskell (version)
import Data.Version (versionBranch)
data ErrorOccurred = Success | Failure deriving (Show, Eq)
-- | Enable debugging output
debug :: Bool
debug = False
-- | Set GHC's verbosity for debugging
ghcVerbosity :: Maybe Int
ghcVerbosity = Nothing -- Just 5
ignoreTypePrefixes :: [String]
ignoreTypePrefixes = ["GHC.Types", "GHC.Base", "GHC.Show", "System.IO",
"GHC.Float", ":Interactive", "GHC.Num", "GHC.IO",
"GHC.Integer.Type"]
typeCleaner :: String -> String
typeCleaner = useStringType . foldl' (.) id (map (`replace` "") fullPrefixes)
where
fullPrefixes = map (++ ".") ignoreTypePrefixes
useStringType = replace "[Char]" "String"
write :: GhcMonad m => String -> m ()
write x = when debug $ liftIO $ hPutStrLn stderr $ "DEBUG: " ++ x
type Interpreter = Ghc
#if MIN_VERSION_ghc(7, 8, 0)
-- GHC 7.8 exports a MonadIO instance for Ghc
#else
instance MonadIO.MonadIO Interpreter where
liftIO = MonadUtils.liftIO
#endif
globalImports :: [String]
globalImports =
[ "import IHaskell.Display()"
, "import qualified Prelude as IHaskellPrelude"
, "import qualified System.Directory as IHaskellDirectory"
, "import qualified IHaskell.Display"
, "import qualified IHaskell.IPython.Stdin"
, "import qualified System.Posix.IO as IHaskellIO"
, "import qualified System.IO as IHaskellSysIO"
]
-- | Run an interpreting action. This is effectively runGhc with
-- initialization and importing. First argument indicates whether `stdin`
-- is handled specially, which cannot be done in a testing environment.
interpret :: Bool -> Interpreter a -> IO a
interpret allowedStdin action = runGhc (Just libdir) $ do
-- If we're in a sandbox, add the relevant package database
sandboxPackages <- liftIO getSandboxPackageConf
initGhci sandboxPackages
case ghcVerbosity of
Just verb -> do dflags <- getSessionDynFlags
void $ setSessionDynFlags $ dflags { verbosity = verb }
Nothing -> return ()
initializeImports
-- Close stdin so it can't be used.
-- Otherwise it'll block the kernel forever.
dir <- liftIO getIHaskellDir
let cmd = printf "IHaskell.IPython.Stdin.fixStdin \"%s\"" dir
when allowedStdin $ void $
runStmt cmd RunToCompletion
initializeItVariable
-- Run the rest of the interpreter
action
-- | Initialize our GHC session with imports and a value for 'it'.
initializeImports :: Interpreter ()
initializeImports = do
-- Load packages that start with ihaskell-*, aren't just IHaskell,
-- and depend directly on the right version of the ihaskell library.
-- Also verify that the packages we load are not broken.
dflags <- getSessionDynFlags
broken <- liftIO getBrokenPackages
displayPackages <- liftIO $ do
(dflags, _) <- initPackages dflags
let Just db = pkgDatabase dflags
packageNames = map (packageIdString . packageConfigId) db
initStr = "ihaskell-"
-- Name of the ihaskell package, e.g. "ihaskell-1.2.3.4"
iHaskellPkgName = initStr ++ intercalate "." (map show (versionBranch version))
dependsOnRight pkg = not $ null $ do
pkg <- db
depId <- depends pkg
dep <- filter ((== depId) . installedPackageId) db
guard (iHaskellPkgName `isPrefixOf` packageIdString (packageConfigId dep))
-- ideally the Paths_ihaskell module could provide a way to get the
-- hash too (ihaskell-0.2.0.5-f2bce922fa881611f72dfc4a854353b9),
-- for now. Things will end badly if you also happen to have an
-- ihaskell-0.2.0.5-ce34eadc18cf2b28c8d338d0f3755502 installed.
iHaskellPkg = case filter (== iHaskellPkgName) packageNames of
[x] -> x
[] -> error ("cannot find required haskell library: " ++ iHaskellPkgName)
_ -> error ("multiple haskell packages " ++ iHaskellPkgName ++ " found")
displayPkgs = [ pkgName
| pkgName <- packageNames,
Just (x:_) <- [stripPrefix initStr pkgName],
pkgName `notElem` broken,
isAlpha x]
return displayPkgs
-- Generate import statements all Display modules.
let capitalize :: String -> String
capitalize (first:rest) = Char.toUpper first : rest
importFmt = "import IHaskell.Display.%s"
toImportStmt :: String -> String
toImportStmt = printf importFmt . capitalize . (!! 1) . split "-"
displayImports = map toImportStmt displayPackages
-- Import implicit prelude.
importDecl <- parseImportDecl "import Prelude"
let implicitPrelude = importDecl { ideclImplicit = True }
-- Import modules.
mapM_ (write . ("Importing " ++ )) displayImports
imports <- mapM parseImportDecl $ globalImports ++ displayImports
setContext $ map IIDecl $ implicitPrelude : imports
-- | Give a value for the `it` variable.
initializeItVariable :: Interpreter ()
initializeItVariable = do
-- This is required due to the way we handle `it` in the wrapper
-- statements - if it doesn't exist, the first statement will fail.
write "Setting `it` to unit."
void $ runStmt "let it = ()" RunToCompletion
-- | Publisher for IHaskell outputs. The first argument indicates whether
-- this output is final (true) or intermediate (false).
type Publisher = (EvaluationResult -> IO ())
-- | Output of a command evaluation.
data EvalOut = EvalOut {
evalStatus :: ErrorOccurred,
evalResult :: Display,
evalState :: KernelState,
evalPager :: String,
evalComms :: [CommInfo]
}
-- | Evaluate some IPython input code.
evaluate :: KernelState -- ^ The kernel state.
-> String -- ^ Haskell code or other interpreter commands.
-> (EvaluationResult -> IO ()) -- ^ Function used to publish data outputs.
-> Interpreter KernelState
evaluate kernelState code output = do
cmds <- parseString (strip code)
let execCount = getExecutionCounter kernelState
when (getLintStatus kernelState /= LintOff) $ liftIO $ do
lintSuggestions <- lint cmds
unless (noResults lintSuggestions) $
output $ FinalResult lintSuggestions "" []
updated <- runUntilFailure kernelState (map unloc cmds ++ [storeItCommand execCount])
return updated {
getExecutionCounter = execCount + 1
}
where
noResults (Display res) = null res
noResults (ManyDisplay res) = all noResults res
runUntilFailure :: KernelState -> [CodeBlock] -> Interpreter KernelState
runUntilFailure state [] = return state
runUntilFailure state (cmd:rest) = do
evalOut <- evalCommand output cmd state
-- Get displayed channel outputs.
-- Merge them with normal display outputs.
dispsIO <- extractValue "IHaskell.Display.displayFromChan"
dispsMay <- liftIO dispsIO
let result =
case dispsMay of
Nothing -> evalResult evalOut
Just disps -> evalResult evalOut <> disps
helpStr = evalPager evalOut
-- Output things only if they are non-empty.
let empty = noResults result && null helpStr && null (evalComms evalOut)
unless empty $
liftIO $ output $ FinalResult result helpStr (evalComms evalOut)
-- Make sure to clear all comms we've started.
let newState = evalState evalOut { evalComms = [] }
case evalStatus evalOut of
Success -> runUntilFailure newState rest
Failure -> return newState
storeItCommand execCount = Statement $ printf "let it%d = it" execCount
extractValue :: Typeable a => String -> Interpreter a
extractValue expr = do
compiled <- dynCompileExpr expr
case fromDynamic compiled of
Nothing -> error "Expecting value!"
Just result -> return result
safely :: KernelState -> Interpreter EvalOut -> Interpreter EvalOut
safely state = ghandle handler . ghandle sourceErrorHandler
where
handler :: SomeException -> Interpreter EvalOut
handler exception =
return EvalOut {
evalStatus = Failure,
evalResult = displayError $ show exception,
evalState = state,
evalPager = "",
evalComms = []
}
sourceErrorHandler :: SourceError -> Interpreter EvalOut
sourceErrorHandler srcerr = do
let msgs = bagToList $ srcErrorMessages srcerr
errStrs <- forM msgs $ \msg -> do
shortStr <- doc $ errMsgShortDoc msg
contextStr <- doc $ errMsgExtraInfo msg
return $ unlines [shortStr, contextStr]
let fullErr = unlines errStrs
return EvalOut {
evalStatus = Failure,
evalResult = displayError fullErr,
evalState = state,
evalPager = "",
evalComms = []
}
wrapExecution :: KernelState
-> Interpreter Display
-> Interpreter EvalOut
wrapExecution state exec = safely state $ exec >>= \res ->
return EvalOut {
evalStatus = Success,
evalResult = res,
evalState = state,
evalPager = "",
evalComms = []
}
-- | Return the display data for this command, as well as whether it
-- resulted in an error.
evalCommand :: Publisher -> CodeBlock -> KernelState -> Interpreter EvalOut
evalCommand _ (Import importStr) state = wrapExecution state $ do
write $ "Import: " ++ importStr
evalImport importStr
-- Warn about `it` variable.
return $ if "Test.Hspec" `isInfixOf` importStr
then displayError $ "Warning: Hspec is unusable in IHaskell until the resolution of GHC bug #8639." ++
"\nThe variable `it` is shadowed and cannot be accessed, even in qualified form."
else mempty
evalCommand _ (Module contents) state = wrapExecution state $ do
write $ "Module:\n" ++ contents
-- Write the module contents to a temporary file in our work directory
namePieces <- getModuleName contents
liftIO (print namePieces)
let directory = "./" ++ intercalate "/" (init namePieces) ++ "/"
filename = last namePieces ++ ".hs"
liftIO $ do
createDirectoryIfMissing True directory
writeFile (fpFromString $ directory ++ filename) contents
-- Clear old modules of this name
let modName = intercalate "." namePieces
removeTarget $ TargetModule $ mkModuleName modName
removeTarget $ TargetFile filename Nothing
-- Remember which modules we've loaded before.
importedModules <- getContext
let -- Get the dot-delimited pieces of the module name.
moduleNameOf :: InteractiveImport -> [String]
moduleNameOf (IIDecl decl) = split "." . moduleNameString . unLoc . ideclName $ decl
moduleNameOf (IIModule imp) = split "." . moduleNameString $ imp
-- Return whether this module prevents the loading of the one we're
-- trying to load. If a module B exist, we cannot load A.B. All
-- modules must have unique last names (where A.B has last name B).
-- However, we *can* just reload a module.
preventsLoading mod =
let pieces = moduleNameOf mod in
last namePieces == last pieces && namePieces /= pieces
-- If we've loaded anything with the same last name, we can't use this.
-- Otherwise, GHC tries to load the original *.hs fails and then fails.
case find preventsLoading importedModules of
-- If something prevents loading this module, return an error.
Just previous -> do
let prevLoaded = intercalate "." (moduleNameOf previous)
return $ displayError $
printf "Can't load module %s because already loaded %s" modName prevLoaded
-- Since nothing prevents loading the module, compile and load it.
Nothing -> doLoadModule modName modName
-- | Directives set via `:set`.
evalCommand output (Directive SetDynFlag flags) state =
case words flags of
-- For a single flag.
[flag] -> do
write $ "DynFlags: " ++ flags
-- Check if this is setting kernel options.
case find (elem flag . getSetName) kernelOpts of
-- If this is a kernel option, just set it.
Just (KernelOpt _ _ updater) ->
return EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = updater state,
evalPager = "",
evalComms = []
}
-- If not a kernel option, must be a dyn flag.
Nothing -> do
errs <- setFlags [flag]
let display = case errs of
[] -> mempty
_ -> displayError $ intercalate "\n" errs
-- For -XNoImplicitPrelude, remove the Prelude import.
-- For -XImplicitPrelude, add it back in.
case flag of
"-XNoImplicitPrelude" ->
evalImport "import qualified Prelude as Prelude"
"-XImplicitPrelude" -> do
importDecl <- parseImportDecl "import Prelude"
let implicitPrelude = importDecl { ideclImplicit = True }
imports <- getContext
setContext $ IIDecl implicitPrelude : imports
_ -> return ()
return EvalOut {
evalStatus = Success,
evalResult = display,
evalState = state,
evalPager = "",
evalComms = []
}
-- Apply many flags.
flag:manyFlags -> do
firstEval <- evalCommand output (Directive SetDynFlag flag) state
case evalStatus firstEval of
Failure -> return firstEval
Success -> do
let newState = evalState firstEval
results = evalResult firstEval
restEval <- evalCommand output (Directive SetDynFlag $ unwords manyFlags) newState
return restEval {
evalResult = results ++ evalResult restEval
}
evalCommand output (Directive SetExtension opts) state = do
write $ "Extension: " ++ opts
let set = concatMap (" -X" ++) $ words opts
evalCommand output (Directive SetDynFlag set) state
evalCommand a (Directive SetOption opts) state = do
write $ "Option: " ++ opts
let (existing, nonExisting) = partition optionExists $ words opts
if not $ null nonExisting
then
let err = "No such options: " ++ intercalate ", " nonExisting in
return EvalOut {
evalStatus = Failure,
evalResult = displayError err,
evalState = state,
evalPager = "",
evalComms = []
}
else
let options = mapMaybe findOption $ words opts
updater = foldl' (.) id $ map getUpdateKernelState options in
return EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = updater state,
evalPager = "",
evalComms = []
}
where
optionExists = isJust . findOption
findOption opt =
find (elem opt . getOptionName) kernelOpts
evalCommand _ (Directive GetType expr) state = wrapExecution state $ do
write $ "Type: " ++ expr
formatType <$> ((expr ++ " :: ") ++ ) <$> getType expr
evalCommand _ (Directive GetKind expr) state = wrapExecution state $ do
write $ "Kind: " ++ expr
(_, kind) <- GHC.typeKind False expr
flags <- getSessionDynFlags
let typeStr = showSDocUnqual flags $ ppr kind
return $ formatType $ expr ++ " :: " ++ typeStr
evalCommand _ (Directive LoadFile name) state = wrapExecution state $ do
write $ "Load: " ++ name
let filename = if endswith ".hs" name
then name
else name ++ ".hs"
contents <- readFile $ fpFromString filename
modName <- intercalate "." <$> getModuleName contents
doLoadModule filename modName
evalCommand publish (Directive ShellCmd ('!':cmd)) state = wrapExecution state $
case words cmd of
"cd":dirs -> do
-- Get home so we can replace '~` with it.
homeEither <- liftIO (try $ getEnv "HOME" :: IO (Either SomeException String))
let home = case homeEither of
Left _ -> "~"
Right val -> val
let directory = replace "~" home $ unwords dirs
exists <- liftIO $ doesDirectoryExist directory
if exists
then do
-- Set the directory in IHaskell native code, for future shell
-- commands. This doesn't set it for user code, though.
liftIO $ setCurrentDirectory directory
-- Set the directory for user code.
let cmd = printf "IHaskellDirectory.setCurrentDirectory \"%s\"" $
replace " " "\\ " $
replace "\"" "\\\"" directory
runStmt cmd RunToCompletion
return mempty
else
return $ displayError $ printf "No such directory: '%s'" directory
cmd -> liftIO $ do
(readEnd, writeEnd) <- createPipe
handle <- fdToHandle writeEnd
pipe <- fdToHandle readEnd
let initProcSpec = shell $ unwords cmd
procSpec = initProcSpec {
std_in = Inherit,
std_out = UseHandle handle,
std_err = UseHandle handle
}
(_, _, _, process) <- createProcess procSpec
-- Accumulate output from the process.
outputAccum <- liftIO $ newMVar ""
-- Start a loop to publish intermediate results.
let
-- Compute how long to wait between reading pieces of the output.
-- `threadDelay` takes an argument of microseconds.
ms = 1000
delay = 100 * ms
-- Maximum size of the output (after which we truncate).
maxSize = 100 * 1000
incSize = 200
output str = publish $ IntermediateResult $ Display [plain str]
loop = do
-- Wait and then check if the computation is done.
threadDelay delay
-- Read next chunk and append to accumulator.
nextChunk <- readChars pipe "\n" incSize
modifyMVar_ outputAccum (return . (++ nextChunk))
-- Check if we're done.
exitCode <- getProcessExitCode process
let computationDone = isJust exitCode
when computationDone $ do
nextChunk <- readChars pipe "" maxSize
modifyMVar_ outputAccum (return . (++ nextChunk))
if not computationDone
then do
-- Write to frontend and repeat.
readMVar outputAccum >>= output
loop
else do
out <- readMVar outputAccum
case fromJust exitCode of
ExitSuccess -> return $ Display [plain out]
ExitFailure code -> do
let errMsg = "Process exited with error code " ++ show code
htmlErr = printf "%s" errMsg
return $ Display [plain $ out ++ "\n" ++ errMsg,
html $ printf "%s" out ++ htmlErr]
loop
-- This is taken largely from GHCi's info section in InteractiveUI.
evalCommand _ (Directive GetHelp _) state = do
write "Help via :help or :?."
return EvalOut {
evalStatus = Success,
evalResult = Display [out],
evalState = state,
evalPager = "",
evalComms = []
}
where out = plain $ intercalate "\n"
["The following commands are available:"
," :extension - Enable a GHC extension."
," :extension No - Disable a GHC extension."
," :type - Print expression type."
," :info - Print all info for a name."
," :hoogle - Search for a query on Hoogle."
," :doc - Get documentation for an identifier via Hogole."
," :set -XFlag -Wall - Set an option (like ghci)."
," :option - Set an option."
," :option no- - Unset an option."
," :?, :help - Show this help text."
,""
,"Any prefix of the commands will also suffice, e.g. use :ty for :type."
,""
,"Options:"
," lint - enable or disable linting."
," svg - use svg output (cannot be resized)."
," show-types - show types of all bound names"
," show-errors - display Show instance missing errors normally."
]
-- This is taken largely from GHCi's info section in InteractiveUI.
evalCommand _ (Directive GetInfo str) state = safely state $ do
write $ "Info: " ++ str
-- Get all the info for all the names we're given.
strings <- getDescription str
let output = case getFrontend state of
IPythonConsole -> unlines strings
IPythonNotebook -> unlines (map htmlify strings)
htmlify str =
printf "" str
++ script
script =
""
return EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = state,
evalPager = output,
evalComms = []
}
evalCommand _ (Directive SearchHoogle query) state = safely state $ do
results <- liftIO $ Hoogle.search query
return $ hoogleResults state results
evalCommand _ (Directive GetDoc query) state = safely state $ do
results <- liftIO $ Hoogle.document query
return $ hoogleResults state results
evalCommand output (Statement stmt) state = wrapExecution state $ do
write $ "Statement:\n" ++ stmt
let outputter str = output $ IntermediateResult $ Display [plain str]
(printed, result) <- capturedStatement outputter stmt
case result of
RunOk names -> do
dflags <- getSessionDynFlags
let allNames = map (showPpr dflags) names
isItName name =
name == "it" ||
name == "it" ++ show (getExecutionCounter state)
nonItNames = filter (not . isItName) allNames
output = [plain printed | not . null $ strip printed]
write $ "Names: " ++ show allNames
-- Display the types of all bound names if the option is on.
-- This is similar to GHCi :set +t.
if not $ useShowTypes state
then return $ Display output
else do
-- Get all the type strings.
types <- forM nonItNames $ \name -> do
theType <- showSDocUnqual dflags . ppr <$> exprType name
return $ name ++ " :: " ++ theType
let joined = unlines types
htmled = unlines $ map formatGetType types
return $ case extractPlain output of
"" -> Display [html htmled]
-- Return plain and html versions.
-- Previously there was only a plain version.
text -> Display
[plain $ joined ++ "\n" ++ text,
html $ htmled ++ mono text]
RunException exception -> throw exception
RunBreak{} -> error "Should not break."
evalCommand output (Expression expr) state = do
write $ "Expression:\n" ++ expr
-- Try to use `display` to convert our type into the output
-- Dislay If typechecking fails and there is no appropriate
-- typeclass instance, this will throw an exception and thus `attempt` will
-- return False, and we just resort to plaintext.
let displayExpr = printf "(IHaskell.Display.display (%s))" expr :: String
canRunDisplay <- attempt $ exprType displayExpr
-- Check if this is a widget.
let widgetExpr = printf "(IHaskell.Display.Widget (%s))" expr :: String
isWidget <- attempt $ exprType widgetExpr
write $ "Can Display: " ++ show canRunDisplay
write $ " Is Widget: " ++ show canRunDisplay
if canRunDisplay
then do
-- Use the display. As a result, `it` is set to the output.
out <- useDisplay displayExpr
-- Register the `it` object as a widget.
if isWidget
then registerWidget out
else return out
else do
-- Evaluate this expression as though it's just a statement.
-- The output is bound to 'it', so we can then use it.
evalOut <- evalCommand output (Statement expr) state
let out = evalResult evalOut
showErr = isShowError out
-- If evaluation failed, return the failure. If it was successful, we
-- may be able to use the IHaskellDisplay typeclass.
return $ if not showErr || useShowErrors state
then evalOut
else postprocessShowError evalOut
where
-- Try to evaluate an action. Return True if it succeeds and False if
-- it throws an exception. The result of the action is discarded.
attempt :: Interpreter a -> Interpreter Bool
attempt action = gcatch (action >> return True) failure
where failure :: SomeException -> Interpreter Bool
failure _ = return False
-- Check if the error is due to trying to print something that doesn't
-- implement the Show typeclass.
isShowError (ManyDisplay _) = False
isShowError (Display errs) =
-- Note that we rely on this error message being 'type cleaned', so
-- that `Show` is not displayed as GHC.Show.Show.
startswith "No instance for (Show" msg &&
isInfixOf " arising from a use of `print'" msg
where msg = extractPlain errs
isSvg (DisplayData mime _) = mime == MimeSvg
removeSvg :: Display -> Display
removeSvg (Display disps) = Display $ filter (not . isSvg) disps
removeSvg (ManyDisplay disps) = ManyDisplay $ map removeSvg disps
useDisplay displayExpr = do
-- If there are instance matches, convert the object into
-- a Display. We also serialize it into a bytestring. We get
-- the bytestring IO action as a dynamic and then convert back to
-- a bytestring, which we promptly unserialize. Note that
-- attempting to do this without the serialization to binary and
-- back gives very strange errors - all the types match but it
-- refuses to decode back into a Display.
-- Suppress output, so as not to mess up console.
-- First, evaluate the expression in such a way that we have access to `it`.
io <- isIO expr
let stmtTemplate = if io
then "it <- (%s)"
else "let { it = %s }"
evalOut <- evalCommand output (Statement $ printf stmtTemplate expr) state
case evalStatus evalOut of
Failure -> return evalOut
Success -> wrapExecution state $ do
-- Compile the display data into a bytestring.
let compileExpr = "fmap IHaskell.Display.serializeDisplay (IHaskell.Display.display it)"
displayedBytestring <- dynCompileExpr compileExpr
-- Convert from the bytestring into a display.
case fromDynamic displayedBytestring of
Nothing -> error "Expecting lazy Bytestring"
Just bytestringIO -> do
bytestring <- liftIO bytestringIO
case Serialize.decode bytestring of
Left err -> error err
Right display ->
return $
if useSvg state
then display :: Display
else removeSvg display
registerWidget :: EvalOut -> Ghc EvalOut
registerWidget evalOut =
case evalStatus evalOut of
Failure -> return evalOut
Success -> do
element <- dynCompileExpr "IHaskell.Display.Widget it"
case fromDynamic element of
Nothing -> error "Expecting widget"
Just widget -> do
-- Stick the widget in the kernel state.
uuid <- liftIO UUID.random
let state = evalState evalOut
newComms = Map.insert uuid widget $ openComms state
state' = state { openComms = newComms }
-- Store the fact that we should start this comm.
return evalOut {
evalComms = CommInfo widget uuid (targetName widget) : evalComms evalOut,
evalState = state'
}
isIO expr = attempt $ exprType $ printf "((\\x -> x) :: IO a -> IO a) (%s)" expr
postprocessShowError :: EvalOut -> EvalOut
postprocessShowError evalOut = evalOut { evalResult = Display $ map postprocess disps }
where
Display disps = evalResult evalOut
text = extractPlain disps
postprocess (DisplayData MimeHtml _) = html $ printf fmt unshowableType (formatErrorWithClass "err-msg collapse" text) script
where
fmt = "Unshowable:%s%s
"
script = unlines [
"$('#unshowable').on('click', function(e) {",
" e.preventDefault();",
" var $this = $(this);",
" var $collapse = $this.closest('.collapse-group').find('.err-msg');",
" $collapse.collapse('toggle');",
"});"
]
postprocess other = other
unshowableType = fromMaybe "" $ do
let pieces = words text
before = takeWhile (/= "arising") pieces
after = init $ unwords $ tail $ dropWhile (/= "(Show") before
firstChar <- headMay after
return $ if firstChar == '('
then init $ tail after
else after
evalCommand _ (Declaration decl) state = wrapExecution state $ do
write $ "Declaration:\n" ++ decl
boundNames <- evalDeclarations decl
let nonDataNames = filter (not . isUpper . head) boundNames
-- Display the types of all bound names if the option is on.
-- This is similar to GHCi :set +t.
if not $ useShowTypes state
then return mempty
else do
-- Get all the type strings.
dflags <- getSessionDynFlags
types <- forM nonDataNames $ \name -> do
theType <- showSDocUnqual dflags . ppr <$> exprType name
return $ name ++ " :: " ++ theType
return $ Display [html $ unlines $ map formatGetType types]
evalCommand _ (TypeSignature sig) state = wrapExecution state $
-- We purposefully treat this as a "success" because that way execution
-- continues. Empty type signatures are likely due to a parse error later
-- on, and we want that to be displayed.
return $ displayError $ "The type signature " ++ sig ++
"\nlacks an accompanying binding."
evalCommand _ (ParseError loc err) state = do
write "Parse Error."
return EvalOut {
evalStatus = Failure,
evalResult = displayError $ formatParseError loc err,
evalState = state,
evalPager = "",
evalComms = []
}
hoogleResults :: KernelState -> [Hoogle.HoogleResult] -> EvalOut
hoogleResults state results = EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = state,
evalPager = output,
evalComms = []
}
where
fmt =
case getFrontend state of
IPythonNotebook -> Hoogle.HTML
IPythonConsole -> Hoogle.Plain
output = unlines $ map (Hoogle.render fmt) results
-- Read from a file handle until we hit a delimiter or until we've read
-- as many characters as requested
readChars :: Handle -> String -> Int -> IO String
-- If we're done reading, return nothing.
readChars handle delims 0 = return []
readChars handle delims nchars = do
-- Try reading a single character. It will throw an exception if the
-- handle is already closed.
tryRead <- gtry $ hGetChar handle :: IO (Either SomeException Char)
case tryRead of
Right char ->
-- If this is a delimiter, stop reading.
if char `elem` delims
then return [char]
else do
next <- readChars handle delims (nchars - 1)
return $ char:next
-- An error occurs at the end of the stream, so just stop reading.
Left _ -> return []
doLoadModule :: String -> String -> Ghc Display
doLoadModule name modName = do
-- Remember which modules we've loaded before.
importedModules <- getContext
flip gcatch (unload importedModules) $ do
-- Compile loaded modules.
flags <- getSessionDynFlags
#if MIN_VERSION_ghc(7,8,0)
let objTarget = defaultObjectTarget platform
platform = targetPlatform flags
#else
let objTarget = defaultObjectTarget
#endif
setSessionDynFlags flags{ hscTarget = objTarget }
-- Clear old targets to be sure.
setTargets []
load LoadAllTargets
-- Load the new target.
target <- guessTarget name Nothing
addTarget target
result <- load LoadAllTargets
-- Reset the context, since loading things screws it up.
initializeItVariable
-- Add imports
importDecl <- parseImportDecl $ "import " ++ modName
let implicitImport = importDecl { ideclImplicit = True }
setContext $ IIDecl implicitImport : importedModules
-- Switch back to interpreted mode.
flags <- getSessionDynFlags
setSessionDynFlags flags{ hscTarget = HscInterpreted }
case result of
Succeeded -> return mempty
Failed -> return $ displayError $ "Failed to load module " ++ modName
where
unload :: [InteractiveImport] -> SomeException -> Ghc Display
unload imported exception = do
print $ show exception
-- Explicitly clear targets
setTargets []
load LoadAllTargets
-- Switch to interpreted mode!
flags <- getSessionDynFlags
setSessionDynFlags flags{ hscTarget = HscInterpreted }
-- Return to old context, make sure we have `it`.
setContext imported
initializeItVariable
return $ displayError $ "Failed to load module " ++ modName ++ ": " ++ show exception
keepingItVariable :: Interpreter a -> Interpreter a
keepingItVariable act = do
-- Generate the it variable temp name
gen <- liftIO getStdGen
let rand = take 20 $ randomRs ('0', '9') gen
var name = name ++ rand
goStmt s = runStmt s RunToCompletion
itVariable = var "it_var_temp_"
goStmt $ printf "let %s = it" itVariable
val <- act
goStmt $ printf "let it = %s" itVariable
act
capturedStatement :: (String -> IO ()) -- ^ Function used to publish intermediate output.
-> String -- ^ Statement to evaluate.
-> Interpreter (String, RunResult) -- ^ Return the output and result.
capturedStatement output stmt = do
-- Generate random variable names to use so that we cannot accidentally
-- override the variables by using the right names in the terminal.
gen <- liftIO getStdGen
let
-- Variable names generation.
rand = take 20 $ randomRs ('0', '9') gen
var name = name ++ rand
-- Variables for the pipe input and outputs.
readVariable = var "file_read_var_"
writeVariable = var "file_write_var_"
-- Variable where to store old stdout.
oldVariable = var "old_var_"
-- Variable used to store true `it` value.
itVariable = var "it_var_"
voidpf str = printf $ str ++ " IHaskellPrelude.>> IHaskellPrelude.return ()"
-- Statements run before the thing we're evaluating.
initStmts =
[ printf "let %s = it" itVariable
, printf "(%s, %s) <- IHaskellIO.createPipe" readVariable writeVariable
, printf "%s <- IHaskellIO.dup IHaskellIO.stdOutput" oldVariable
, voidpf "IHaskellIO.dupTo %s IHaskellIO.stdOutput" writeVariable
, voidpf "IHaskellSysIO.hSetBuffering IHaskellSysIO.stdout IHaskellSysIO.NoBuffering"
, printf "let it = %s" itVariable
]
-- Statements run after evaluation.
postStmts =
[ printf "let %s = it" itVariable
, voidpf "IHaskellSysIO.hFlush IHaskellSysIO.stdout"
, voidpf "IHaskellIO.dupTo %s IHaskellIO.stdOutput" oldVariable
, voidpf "IHaskellIO.closeFd %s" writeVariable
, printf "let it = %s" itVariable
]
pipeExpr = printf "let %s = %s" (var "pipe_var_") readVariable
goStmt :: String -> Ghc RunResult
goStmt s = runStmt s RunToCompletion
-- Initialize evaluation context.
void $ forM initStmts goStmt
-- Get the pipe to read printed output from.
-- This is effectively the source code of dynCompileExpr from GHC API's
-- InteractiveEval. However, instead of using a `Dynamic` as an
-- intermediary, it just directly reads the value. This is incredibly
-- unsafe! However, for some reason the `getContext` and `setContext`
-- required by dynCompileExpr (to import and clear Data.Dynamic) cause
-- issues with data declarations being updated (e.g. it drops newer
-- versions of data declarations for older ones for unknown reasons).
-- First, compile down to an HValue.
Just (_, hValues, _) <- withSession $ liftIO . flip hscStmt pipeExpr
-- Then convert the HValue into an executable bit, and read the value.
pipe <- liftIO $ do
fd <- head <$> unsafeCoerce hValues
fdToHandle fd
-- Read from a file handle until we hit a delimiter or until we've read
-- as many characters as requested
let
readChars :: Handle -> String -> Int -> IO String
-- If we're done reading, return nothing.
readChars handle delims 0 = return []
readChars handle delims nchars = do
-- Try reading a single character. It will throw an exception if the
-- handle is already closed.
tryRead <- gtry $ hGetChar handle :: IO (Either SomeException Char)
case tryRead of
Right char ->
-- If this is a delimiter, stop reading.
if char `elem` delims
then return [char]
else do
next <- readChars handle delims (nchars - 1)
return $ char:next
-- An error occurs at the end of the stream, so just stop reading.
Left _ -> return []
-- Keep track of whether execution has completed.
completed <- liftIO $ newMVar False
finishedReading <- liftIO newEmptyMVar
outputAccum <- liftIO $ newMVar ""
-- Start a loop to publish intermediate results.
let
-- Compute how long to wait between reading pieces of the output.
-- `threadDelay` takes an argument of microseconds.
ms = 1000
delay = 100 * ms
-- How much to read each time.
chunkSize = 100
-- Maximum size of the output (after which we truncate).
maxSize = 100 * 1000
loop = do
-- Wait and then check if the computation is done.
threadDelay delay
computationDone <- readMVar completed
if not computationDone
then do
-- Read next chunk and append to accumulator.
nextChunk <- readChars pipe "\n" 100
modifyMVar_ outputAccum (return . (++ nextChunk))
-- Write to frontend and repeat.
readMVar outputAccum >>= output
loop
else do
-- Read remainder of output and accumulate it.
nextChunk <- readChars pipe "" maxSize
modifyMVar_ outputAccum (return . (++ nextChunk))
-- We're done reading.
putMVar finishedReading True
liftIO $ forkIO loop
result <- gfinally (goStmt stmt) $ do
-- Execution is done.
liftIO $ modifyMVar_ completed (const $ return True)
-- Finalize evaluation context.
void $ forM postStmts goStmt
-- Once context is finalized, reading can finish.
-- Wait for reading to finish to that the output accumulator is
-- completely filled.
liftIO $ takeMVar finishedReading
printedOutput <- liftIO $ readMVar outputAccum
return (printedOutput, result)
formatError :: ErrMsg -> String
formatError = formatErrorWithClass "err-msg"
formatErrorWithClass :: String -> ErrMsg -> String
formatErrorWithClass cls =
printf "%s" cls .
replace "\n" "
" .
replace useDashV "" .
replace "Ghci" "IHaskell" .
fixDollarSigns .
rstrip .
typeCleaner
where
fixDollarSigns = replace "$" "$"
useDashV = "\nUse -v to see a list of the files searched for."
isShowError err =
startswith "No instance for (Show" err &&
isInfixOf " arising from a use of `print'" err
formatParseError :: StringLoc -> String -> ErrMsg
formatParseError (Loc line col) =
printf "Parse error (line %d, column %d): %s" line col
formatGetType :: String -> String
formatGetType = printf "%s"
formatType :: String -> Display
formatType typeStr = Display [plain typeStr, html $ formatGetType typeStr]
displayError :: ErrMsg -> Display
displayError msg = Display [plain . typeCleaner $ msg, html $ formatError msg]
mono :: String -> String
mono = printf "%s"