Tutorial on how to use effects

[dambaev]

Hi, during investigating topic of Free monads, I have found your blog post about performance of extensible. I have found it interesting and tried to start using, but struggling to do it.
Other libraries has more examples to compare.
For example, I can't get into how to implement with extensible the example for freer:

{-# LANGUAGE GADTs #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE DataKinds #-}
module Console where

import Control.Monad.Freer
import Control.Monad.Freer.Internal
import System.Exit hiding (ExitSuccess)

--------------------------------------------------------------------------------
                               -- Effect Model --
--------------------------------------------------------------------------------
data Console s where
    PutStrLn    :: String -> Console ()
    GetLine     :: Console String
    ExitSuccess :: Console ()

putStrLn' :: Member Console r => String -> Eff r ()
putStrLn' = send . PutStrLn

getLine' :: Member Console r => Eff r String
getLine' = send GetLine

exitSuccess' :: Member Console r => Eff r ()
exitSuccess' = send ExitSuccess

--------------------------------------------------------------------------------
                          -- Effectful Interpreter --
--------------------------------------------------------------------------------
runConsole :: Eff '[Console] w -> IO w
runConsole (Val x) = return x
runConsole (E u q) =
    case extract u of
        PutStrLn msg -> putStrLn msg >>  runConsole (qApp q ())
        GetLine      -> getLine      >>= \s -> runConsole (qApp q s)
        ExitSuccess  -> exitSuccess

--------------------------------------------------------------------------------
                             -- Pure Interpreter --
--------------------------------------------------------------------------------
runConsolePure :: [String] -> Eff '[Console] w -> [String]
runConsolePure inputs req =
    reverse . snd $ run (handleRelayS (inputs, []) (\s _ -> pure s) go req)
  where
    go  :: ([String], [String])
        -> Console v
        -> (([String], [String]) -> Arr '[] v ([String], [String]))
        -> Eff '[] ([String], [String])
    go (is,   os) (PutStrLn msg) q = q (is, msg : os) ()
    go (i:is, os) GetLine        q = q (is, os) i
    go ([],   _ ) GetLine        _ = error "Not enough lines"
    go (_,    os) ExitSuccess    _ = pure ([], os)

I am aware of extensible's example/effects.hs, but it does not compiling:

/mnt/localdata/share/devel/haskell/ext-test/app/Main.hs:43:27: error:
    • Expected kind ‘[Assoc * (* -> *)]’,
        but ‘Example’ has kind ‘[Assoc
                                   ghc-prim-0.5.1.1:GHC.Types.Symbol (* -> *)]’
    • In the first argument of ‘Methods’, namely ‘Example’
      In the type signature: example :: Int -> Methods Example IO
   |
43 | example :: Int -> Methods Example IO
   |                           ^^^^^^^