{-# LANGUAGE ExistentialQuantification #-}
module Language.Haskell.GhcMod.Error (
GhcModError(..)
, GmError
, gmeDoc
, ghcExceptionDoc
, liftMaybe
, overrideError
, modifyError
, modifyError'
, modifyGmError
, tryFix
, GHandler(..)
, gcatches
, module Control.Monad.Error
, module Control.Exception
) where
import Control.Arrow hiding ((<+>))
import Control.Exception
import Control.Monad.Error hiding (MonadIO, liftIO)
import qualified Data.Set as Set
import Data.List
import Data.Version
import System.Process (showCommandForUser)
import Text.PrettyPrint
import Text.Printf
import Exception
import Panic
import Config (cProjectVersion, cHostPlatformString)
import Paths_ghc_mod (version)
import Language.Haskell.GhcMod.Types
import Language.Haskell.GhcMod.Pretty
type GmError m = MonadError GhcModError m
gmeDoc :: GhcModError -> Doc
gmeDoc e = case e of
GMENoMsg ->
text "Unknown error"
GMEString msg ->
text msg
GMECabalConfigure msg ->
text "Configuring cabal project failed" <+>: gmeDoc msg
GMEStackConfigure msg ->
text "Configuring stack project failed" <+>: gmeDoc msg
GMEStackBootstrap msg ->
text "Bootstrapping stack project environment failed" <+>: gmeDoc msg
GMECabalCompAssignment ctx ->
text "Could not find a consistent component assignment for modules:" $$
(nest 4 $ foldr ($+$) empty $ map ctxDoc ctx) $$
text "" $$
(if all (Set.null . snd) ctx
then noComponentSuggestions
else empty) $$
text "- To find out which components ghc-mod knows about try:" $$
nest 4 (backticks $ text "ghc-mod debug")
where
noComponentSuggestions =
text "- Are some of these modules part of a test and or benchmark?\
\ Try enabling them:" $$
nest 4 (backticks $ text "cabal configure --enable-tests [--enable-benchmarks]")
backticks d = char '`' <> d <> char '`'
ctxDoc = moduleDoc *** compsDoc
>>> first (<> colon) >>> uncurry (flip hang 4)
moduleDoc (Left fn) =
text "File " <> quotes (text fn)
moduleDoc (Right mdl) =
text "Module " <> quotes (text $ moduleNameString mdl)
compsDoc sc | Set.null sc = text "has no known components"
compsDoc sc = fsep $ punctuate comma $
map gmComponentNameDoc $ Set.toList sc
GMEProcess _fn cmd args emsg -> let c = showCommandForUser cmd args in
case emsg of
Right err ->
text (printf "Launching system command `%s` failed: " c)
<> gmeDoc err
Left rv -> text $
printf "Launching system command `%s` failed (exited with %d)" c rv
GMENoCabalFile ->
text "No cabal file found."
GMETooManyCabalFiles cfs ->
text $ "Multiple cabal files found. Possible cabal files: \""
++ intercalate "\", \"" cfs ++"\"."
ghcExceptionDoc :: GhcException -> Doc
ghcExceptionDoc e@(CmdLineError _) =
text $ "<command line>: " ++ showGhcException e ""
ghcExceptionDoc (UsageError str) = strDoc str
ghcExceptionDoc (Panic msg) = vcat $ map text $ lines $ printf "\
\GHC panic! (the 'impossible' happened)\n\
\ ghc-mod version %s\n\
\ GHC library version %s for %s:\n\
\ %s\n\
\\n\
\Please report this as a bug: %s\n"
gmVer ghcVer platform msg url
where
gmVer = showVersion version
ghcVer = cProjectVersion
platform = cHostPlatformString
url = "https://github.com/kazu-yamamoto/ghc-mod/issues" :: String
ghcExceptionDoc e = text $ showGhcException e ""
liftMaybe :: MonadError e m => e -> m (Maybe a) -> m a
liftMaybe e action = maybe (throwError e) return =<< action
overrideError :: MonadError e m => e -> m a -> m a
overrideError e action = modifyError (const e) action
modifyError :: MonadError e m => (e -> e) -> m a -> m a
modifyError f action = action `catchError` \e -> throwError $ f e
infixr 0 `modifyError'`
modifyError' :: MonadError e m => m a -> (e -> e) -> m a
modifyError' = flip modifyError
modifyGmError :: (MonadIO m, ExceptionMonad m)
=> (GhcModError -> GhcModError) -> m a -> m a
modifyGmError f a = gcatch a $ \(ex :: GhcModError) -> liftIO $ throwIO (f ex)
tryFix :: MonadError e m => m a -> (e -> m ()) -> m a
tryFix action f = do
action `catchError` \e -> f e >> action
data GHandler m a = forall e . Exception e => GHandler (e -> m a)
gcatches :: (MonadIO m, ExceptionMonad m) => m a -> [GHandler m a] -> m a
gcatches io handlers = io `gcatch` gcatchesHandler handlers
gcatchesHandler :: (MonadIO m, ExceptionMonad m)
=> [GHandler m a] -> SomeException -> m a
gcatchesHandler handlers e = foldr tryHandler (liftIO $ throw e) handlers
where tryHandler (GHandler handler) res
= case fromException e of
Just e' -> handler e'
Nothing -> res