ihaskell-0.3.0.3: src/IHaskell/Eval/Evaluate.hs
{-# LANGUAGE DoAndIfThenElse, NoOverloadedStrings, TypeSynonymInstances #-}
{- | 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 (liftIO, hGetContents, 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 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
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 Paths_ihaskell (version)
import Data.Version (versionBranch)
data ErrorOccurred = Success | Failure deriving (Show, Eq)
debug :: Bool
debug = False
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
instance MonadIO.MonadIO Interpreter where
liftIO = MonadUtils.liftIO
globalImports :: [String]
globalImports =
[ "import IHaskell.Display()"
, "import qualified 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
-- Set the dynamic session flags
originalFlags <- getSessionDynFlags
let dflags = xopt_set originalFlags Opt_ExtendedDefaultRules
-- If we're in a sandbox, add the relevant package database
sandboxPackages <- liftIO getSandboxPackageConf
let pkgConfs = case sandboxPackages of
Nothing -> extraPkgConfs dflags
Just path ->
let pkg = PkgConfFile path in
(pkg:) . extraPkgConfs dflags
void $ setSessionDynFlags $ dflags { hscTarget = HscInterpreted,
ghcLink = LinkInMemory,
pprCols = 300,
extraPkgConfs = pkgConfs }
initializeImports
-- Close stdin so it can't be used.
-- Otherwise it'll block the kernel forever.
dir <- liftIO getIHaskellDir
let cmd = printf "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
--
-- XXX this will try to load broken packages, provided they depend
-- on the right ihaskell version
dflags <- getSessionDynFlags
displayPackages <- liftIO $ do
(dflags, _) <- initPackages dflags
let Just db = pkgDatabase dflags
packageNames = map (packageIdString . packageConfigId) db
initStr = "ihaskell-"
-- "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],
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
}
-- | 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
-- Output things only if they are non-empty.
let result = evalResult evalOut
helpStr = evalPager evalOut
unless (noResults result && null helpStr) $
liftIO $ output $ FinalResult result helpStr
let newState = evalState evalOut
case evalStatus evalOut of
Success -> runUntilFailure newState rest
Failure -> return newState
storeItCommand execCount = Statement $ printf "let it%d = it" execCount
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 = ""
}
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 = ""
}
doc :: GhcMonad m => SDoc -> m String
doc sdoc = do
flags <- getSessionDynFlags
unqual <- getPrintUnqual
let style = mkUserStyle unqual AllTheWay
let cols = pprCols flags
d = runSDoc sdoc (initSDocContext flags style)
return $ Pretty.fullRender Pretty.PageMode cols 1.5 string_txt "" d
where
string_txt :: Pretty.TextDetails -> String -> String
string_txt (Pretty.Chr c) s = c:s
string_txt (Pretty.Str s1) s2 = s1 ++ s2
string_txt (Pretty.PStr s1) s2 = unpackFS s1 ++ s2
string_txt (Pretty.LStr s1 _) s2 = unpackLitString s1 ++ s2
wrapExecution :: KernelState
-> Interpreter Display
-> Interpreter EvalOut
wrapExecution state exec = safely state $ exec >>= \res ->
return EvalOut {
evalStatus = Success,
evalResult = res,
evalState = state,
evalPager = ""
}
-- | Set dynamic flags.
--
-- This was adapted from GHC's InteractiveUI.hs (newDynFlags).
setDynFlags :: [String] -- ^ Flags to set.
-> Interpreter [ErrMsg] -- ^ Errors from trying to set flags.
setDynFlags ext = do
-- Try to parse flags.
flags <- getSessionDynFlags
(flags', unrecognized, warnings) <- parseDynamicFlags flags (map noLoc ext)
-- First, try to check if this flag matches any extension name.
let restorePkg x = x { packageFlags = packageFlags flags }
let restoredPkgs = flags' { packageFlags = packageFlags flags}
GHC.setProgramDynFlags restoredPkgs
GHC.setInteractiveDynFlags restoredPkgs
-- Create the parse errors.
let noParseErrs = map (("Could not parse: " ++) . unLoc) unrecognized
allWarns = map unLoc warnings ++
["-package not supported yet" | packageFlags flags /= packageFlags flags']
warnErrs = map ("Warning: " ++) allWarns
return $ noParseErrs ++ warnErrs
-- | 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
importDecl <- parseImportDecl importStr
context <- getContext
-- If we've imported this implicitly, remove the old import.
let noImplicit = filter (not . implicitImportOf importDecl) context
setContext $ IIDecl importDecl : noImplicit
flags <- getSessionDynFlags
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
where
implicitImportOf :: ImportDecl RdrName -> InteractiveImport -> Bool
implicitImportOf _ (IIModule _) = False
implicitImportOf imp (IIDecl decl) = ideclImplicit decl && ((==) `on` (unLoc . ideclName)) decl imp
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 = ""
}
-- If not a kernel option, must be a dyn flag.
Nothing -> do
errs <- setDynFlags [flag]
let display = case errs of
[] -> mempty
_ -> displayError $ intercalate "\n" errs
return EvalOut {
evalStatus = Success,
evalResult = display,
evalState = state,
evalPager = ""
}
-- Apply many flags.
flag:manyFlags -> do
firstEval <- evalCommand output (Directive SetDynFlag flags) 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 = ""
}
else
let options = mapMaybe findOption $ words opts
updater = foldl' (.) id $ map getUpdateKernelState options in
return EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = updater state,
evalPager = ""
}
where
optionExists = isJust . findOption
findOption opt =
find (elem opt . getOptionName) kernelOpts
evalCommand _ (Directive GetType expr) state = wrapExecution state $ do
write $ "Type: " ++ expr
result <- exprType expr
flags <- getSessionDynFlags
let typeStr = showSDocUnqual flags $ ppr result
return $ formatType typeStr
evalCommand _ (Directive LoadFile name) state = wrapExecution state $ do
write $ "Load: " ++ name
let filename = if endswith ".hs" name
then name
else name ++ ".hs"
let modName = replace "/" "." $
if endswith ".hs" name
then replace ".hs" "" name
else name
doLoadModule filename modName
evalCommand publish (Directive ShellCmd ('!':cmd)) state = wrapExecution state $ liftIO $
case words cmd of
"cd":dirs -> do
-- Get home so we can replace '~` with it.
homeEither <- try $ getEnv "HOME" :: IO (Either SomeException String)
let home = case homeEither of
Left _ -> "~"
Right val -> val
let directory = replace "~" home $ unwords dirs
exists <- doesDirectoryExist directory
if exists
then do
setCurrentDirectory directory
return mempty
else
return $ displayError $ printf "No such directory: '%s'" directory
cmd -> 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 "<span class='err-msg'>%s</span>" errMsg
return $ Display [plain $ out ++ "\n" ++ errMsg,
html $ printf "<span class='mono'>%s</span>" 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 = ""
}
where out = plain $ intercalate "\n"
["The following commands are available:"
," :extension <Extension> - Enable a GHC extension."
," :extension No<Extension> - Disable a GHC extension."
," :type <expression> - Print expression type."
," :info <name> - Print all info for a name."
," :hoogle <query> - Search for a query on Hoogle."
," :doc <ident> - Get documentation for an identifier via Hogole."
," :set -XFlag -Wall - Set an option (like ghci)."
," :option <opt> - Set an option."
," :option no-<opt> - 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.
names <- parseName str
maybeInfos <- mapM getInfo names
-- Filter out types that have parents in the same set.
-- GHCi also does this.
let getType (theType, _, _) = theType
infos = catMaybes maybeInfos
allNames = mkNameSet $ map (getName . getType) infos
hasParent info = case tyThingParent_maybe (getType info) of
Just parent -> getName parent `elemNameSet` allNames
Nothing -> False
filteredOutput = filter (not . hasParent) infos
-- Convert to textual data.
let printInfo (thing, fixity, classInstances) =
pprTyThingInContextLoc False thing $$ showFixity fixity $$ vcat (map GHC.pprInstance classInstances)
where
showFixity fixity =
if fixity == GHC.defaultFixity
then empty
else ppr fixity <+> pprInfixName (getName thing)
-- Print nicely.
strings <- mapM (doc . printInfo) filteredOutput
let output = case getFrontend state of
IPythonConsole -> unlines strings
IPythonNotebook -> unlines (map htmlify strings)
htmlify str =
printf "<div style='background: rgb(247, 247, 247);'><form><textarea id='code'>%s</textarea></form></div>" str
++ script
script =
"<script>CodeMirror.fromTextArea(document.getElementById('code'), {mode: 'haskell', readOnly: 'nocursor'});</script>"
return EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = state,
evalPager = output
}
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
if canRunDisplay
then useDisplay displayExpr
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 disps) = Display $ filter (not . isSvg) disps
removeSvg (ManyDisplay disps) = ManyDisplay $ map removeSvg disps
useDisplay displayExpr = wrapExecution state $ do
-- If there are instance matches, convert the object into
-- a Display. We also serialize it into a bytestring. We get
-- the bytestring 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.
out <- capturedStatement (const $ return ()) displayExpr
displayedBytestring <- dynCompileExpr "IHaskell.Display.serializeDisplay it"
case fromDynamic displayedBytestring of
Nothing -> error "Expecting lazy Bytestring"
Just bytestring ->
case Serialize.decode bytestring of
Left err -> error err
Right display ->
return $
if useSvg state
then display
else removeSvg display
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 = "<div class='collapse-group'><span class='btn' href='#' id='unshowable'>Unshowable:<span class='show-type'>%s</span></span>%s</div><script>%s</script>"
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
names <- runDecls decl
dflags <- getSessionDynFlags
let boundNames = map (replace ":Interactive." "" . showPpr dflags) names
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.
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 = ""
}
hoogleResults :: KernelState -> [Hoogle.HoogleResult] -> EvalOut
hoogleResults state results = EvalOut {
evalStatus = Success,
evalResult = mempty,
evalState = state,
evalPager = output
}
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 = flip gcatch unload $ do
-- Compile loaded modules.
flags <- getSessionDynFlags
let objTarget = defaultObjectTarget
setSessionDynFlags flags{ hscTarget = objTarget }
-- Remember which modules we've loaded before.
importedModules <- getContext
-- Create a 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 :: SomeException -> Ghc Display
unload exception = do
-- Explicitly clear targets
setTargets []
load LoadAllTargets
initializeItVariable
return $ displayError $ "Failed to load module " ++ modName ++ ": " ++ show exception
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 ++ " >> 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 s = runStmt s RunToCompletion
-- Initialize evaluation context.
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.
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 "<span class='%s'>%s</span>" cls .
replace "\n" "<br/>" .
replace useDashV "" .
fixDollarSigns .
rstrip .
typeCleaner
where
fixDollarSigns = replace "$" "<span>$</span>"
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 "<span class='get-type'>%s</span>"
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 "<span class='mono'>%s</span>"