server: simple toml config

config.toml

+
+
+port = 8080
+
+tmpdir = "/tmp"
+entrypoint = "main.json"
+lintconfig = "./config.json"
+

package.yaml

@@ -73,3 +73,4 @@ executables:
       - containers
       - microlens
       - microlens-th
+      - tomland

server/Main.hs

@@ -71,7 +71,6 @@ app config =
 
 main :: IO ()
 main = do
+  config' <- loadConfig "./config.toml"
   state <- newMVar defaultState
-  let config = Config "/tmp" 8080 "main.json" "./config.json"
-  config' <- loadConfig config
-  run (port config) (app config' state)
+  run (port config') (app config' state)

server/Server.hs

 {-# LANGUAGE DataKinds                  #-}
 {-# LANGUAGE DeriveAnyClass             #-}
 {-# LANGUAGE DeriveGeneric              #-}
+{-# LANGUAGE DerivingStrategies         #-}
+{-# LANGUAGE FlexibleInstances          #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE KindSignatures             #-}
+{-# LANGUAGE OverloadedStrings          #-}
 {-# LANGUAGE ScopedTypeVariables        #-}
 {-# LANGUAGE TemplateHaskell            #-}
 {-# LANGUAGE TypeApplications           #-}
@@ -23,6 +27,10 @@ import           GHC.Generics         (Generic)
 import           Lens.Micro           (over)
 import           Lens.Micro.TH
 import           LintConfig           (LintConfig')
+import           System.Exit.Compat   (exitFailure)
+import           Toml                 (TomlCodec)
+import qualified Toml
+import           Toml.Codec           ((.=))
 
 
 -- | a reference in a remote git repository
@@ -36,14 +44,21 @@ type family ConfigRes (b :: Bool) a where
   ConfigRes False a = FilePath
 
 -- | the server's configuration
-data Config l = Config
+data Config (loaded :: Bool) = Config
   { tmpdir     :: FilePath
   -- ^ dir to clone git things in
   , port       :: Int
   -- ^ port to bind to
   , entrypoint :: FilePath
-  , lintconfig :: ConfigRes l LintConfig'
-  }
+  , lintconfig :: ConfigRes loaded LintConfig'
+  } deriving Generic
+
+configCodec :: TomlCodec (Config False)
+configCodec = Config
+    <$> Toml.string "tmpdir" .= tmpdir
+    <*> Toml.int "port" .= port
+    <*> Toml.string "entrypoint" .= entrypoint
+    <*> Toml.string "lintconfig" .= lintconfig
 
 data JobStatus =
   Pending | Linted DirResult | Failed Text
@@ -59,9 +74,17 @@ makeLenses ''State
 defaultState :: State
 defaultState = State mempty mempty
 
+loadConfig :: FilePath -> IO (Config True)
+loadConfig path = do
+  res <- Toml.decodeFileEither configCodec path
+  case res of
+    Right config -> loadConfig' config
+    Left err -> do
+      print err
+      exitFailure
 
-loadConfig :: Config False -> IO (Config True)
-loadConfig config = do
+loadConfig' :: Config False -> IO (Config True)
+loadConfig' config = do
   loaded <- LB.readFile (lintconfig config) >>= \res ->
       case eitherDecode res :: Either String LintConfig' of
         Left err   -> error $ "config file invalid: " <> err

walint.cabal

@@ -88,6 +88,7 @@ executable server
     , string-conversions
     , text
     , time
+    , tomland
     , uuid
     , wai
     , walint