Lib3.hs

{-# LANGUAGE DeriveFunctor #-}

module Lib3
  ( executeSql,
    Execution,
    ExecutionAlgebra(..)
  )
where

import Control.Monad.Free (Free (..), liftF)
import DataFrame (DataFrame)
import Data.Time ( UTCTime )

type TableName = String
type FileContent = String
type ErrorMessage = String

data ExecutionAlgebra next
  = LoadFile TableName (FileContent -> next)
  | GetTime (UTCTime -> next)
  -- feel free to add more constructors here
  deriving Functor

type Execution = Free ExecutionAlgebra

loadFile :: TableName -> Execution FileContent
loadFile name = liftF $ LoadFile name id

getTime :: Execution UTCTime
getTime = liftF $ GetTime id

executeSql :: String -> Execution (Either ErrorMessage DataFrame)
executeSql sql = do
    return $ Left "implement me"