Wire-up / registry

0readme.md

https://www.youtube.com/watch?v=fFCcvsbCrH8&t=1571s

Main.hs

{-# language TemplateHaskell #-}

import Brossa.Prelude
import TH
import Things

main :: IO ()
main = $(wire 'app)

TH.hs

{-# language TemplateHaskell #-}

module TH where
import Prelude

import Language.Haskell.TH

wire :: Name -> Q Exp
wire n = do
  i <- reify n
  varE n

Things.hs

module Things where
import Brossa.Prelude
import Data.Aeson (Value)

data ValueStore m = ValueStore {
  store :: Text -> Value -> m (),
  retrieve :: Text -> m (Maybe Value)
  }

data Logger m = Logger {
  log :: Text -> m ()
  }

data Sql m = Sql {
  query :: Text -> m [Value]
  }

valueStore :: Monad m => Sql m -> Logger m -> ValueStore m
valueStore sql logger = ValueStore {
  store = \_text _value -> do logger.log "storing..."
                              void (sql.query "foo"),
  retrieve = \key -> fmap listToMaybe (sql.query key)
  }

app :: ValueStore m -> IO ()
app _ = pure ()