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{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE QuantifiedConstraints #-}
{-# LANGUAGE ImpredicativeTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE OverloadedStrings #-}
module Conftrack.Source (ConfigSource(..), SomeSource(..), Trivial(..)) where
import Conftrack.Value (Key, Value(..), ConfigError(..), Origin)
import Control.Monad.State (get, modify, StateT (..), MonadState (..))
import Data.Map.Strict (Map)
import qualified Data.Map.Strict as M
import Data.Function ((&))
import Data.Text (Text)
import qualified Data.Text as T
class ConfigSource s where
type ConfigState s
fetchValue :: Key -> s -> StateT (ConfigState s) IO (Either ConfigError (Value, Text))
leftovers :: s -> StateT (ConfigState s) IO (Maybe [Key])
data SomeSource = forall source. ConfigSource source
=> SomeSource (source, ConfigState source)
newtype Trivial = Trivial (Map Key Value)
instance ConfigSource Trivial where
type ConfigState Trivial = [Key]
fetchValue key (Trivial tree) = do
case M.lookup key tree of
Nothing -> pure $ Left NotPresent
Just val -> do
modify (key :)
pure $ Right (val, "Trivial source with keys "<> T.pack (show (M.keys tree)))
leftovers (Trivial tree) = do
used <- get
M.keys tree
& filter (`notElem` used)
& Just
& pure
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