A persistent playground

Main.hs

-- nix-shell
-- ghcid -c 'ghci Main.hs'

{-# LANGUAGE GADTs                      #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE QuasiQuotes                #-}
{-# LANGUAGE ScopedTypeVariables        #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TypeFamilies               #-}

import           Control.Monad.Logger        (runLoggingT)
import           Data.ByteString             (ByteString)
import           Database.Persist
import           Database.Persist.Postgresql
import           Database.Persist.TH

share [mkPersist sqlSettings, mkMigrate "migrateAll"] [persistLowerCase|
Post
    name ByteString
    deriving Show
|]

main :: IO ()
main = do
  pool <-
    flip runLoggingT (\_ _ _ _ -> pure ()) $
      createPostgresqlPool "postgresql://postgres:postgres@localhost:5432/bytea" 5
  flip runSqlPool pool $ do
    runMigration migrateAll
    insert $ Post "\160"
    pure ()

shell.nix

{ nixpkgs ? import <nixpkgs> {}, compiler ? "ghc865" }:
let
  inherit (nixpkgs) pkgs;
  ghc = pkgs.haskell.packages.${compiler}.ghcWithPackages (ps: with ps; [
    persistent persistent-template persistent-postgresql
  ]);
in
pkgs.stdenv.mkDerivation {
  name = "persistent-playground";
  buildInputs = [ ghc ];
}