Haskell persistent-mysql example

Main.hs

module Main where

import           Database.Persist
import           Database.Persist.TH
import           Database.Persist.Sql
import           Control.Monad.IO.Class
import           Control.Monad.Reader
import           Database.Persist.MySQL
import           Control.Monad.Logger

share [mkPersist sqlSettings] [persistLowerCase|
Person
    name String
    age Int Maybe
    deriving Show
|]

listPerson :: MonadIO m => SqlPersistT m [Entity Person]
listPerson = selectList [] []

conn :: ConnectInfo
conn = defaultConnectInfo {
    connectPassword = "password",
    connectHost = "0.0.0.0",
    connectDatabase = "learning_sql"
  }

main :: IO ()
main = runStderrLoggingT $ withMySQLPool conn 1 $ runSqlPool $ do
  me <- (entityVal.head) <$> listPerson
  p $ "Name: " <> (personName me)
  case personAge me of
    Just age -> p $ "Age: " <> (show age)
    _ -> return ()
  where
    p = liftIO . putStrLn

package.yaml

name:                haskell-mysql
version:             0.1.0.0
github:              "githubuser/haskell-mysql"
license:             BSD3
author:              "Author name here"
maintainer:          "example@example.com"
copyright:           "2021 Author name here"

extra-source-files:
- README.md
- ChangeLog.md

# Metadata used when publishing your package
# synopsis:            Short description of your package
# category:            Web

# To avoid duplicated efforts in documentation and dealing with the
# complications of embedding Haddock markup inside cabal files, it is
# common to point users to the README.md file.
description:         Please see the README on GitHub at <https://github.com/githubuser/haskell-mysql#readme>

dependencies:
- base >= 4.7 && < 5

library:
  source-dirs: src

executables:
  haskell-mysql-exe:
    main:                Main.hs
    source-dirs:         app
    default-extensions:
    - OverloadedStrings
    - QuasiQuotes
    - TemplateHaskell
    - TypeFamilies
    - GADTs
    - DerivingStrategies
    - GeneralizedNewtypeDeriving
    - StandaloneDeriving
    - UndecidableInstances
    - DataKinds
    - FlexibleInstances
    - MultiParamTypeClasses
    ghc-options:
    - -threaded
    - -rtsopts
    - -with-rtsopts=-N
    dependencies:
    - haskell-mysql
    - persistent
    - persistent-template
    - persistent-mysql
    - mysql
    - bytestring
    - containers
    - mtl
    - monad-logger

tests:
  haskell-mysql-test:
    main:                Spec.hs
    source-dirs:         test
    ghc-options:
    - -threaded
    - -rtsopts
    - -with-rtsopts=-N
    dependencies:
    - haskell-mysql