Update.hs

module Suites.Map.Update where

import Control.Monad.Free
import Control.Monad.Free.TH
import Test.QuickCheck.Instances ()
import Test.Tasty.QuickCheck
import Prelude hiding (delete, insert)

data UpdateF k v c
  = Insert k v c
  | Delete k c
  | Adjust (v -> v) k c
  deriving (Functor)

instance (Show k, Show v, Show c) => Show (UpdateF k v c) where
  showsPrec i =
    showParen (i > 5) . \case
      Insert k v c ->
        showString "Insert "
          . showsPrecInner k
          . showChar ' '
          . showsPrecInner v
          . showChar ' '
          . showsPrecInner c
      Delete k c ->
        showString "Delete "
          . showsPrecInner k
          . showChar ' '
          . showsPrecInner c
      Adjust _ k c ->
        showString "Adjust "
          . showString "<v -> v> "
          . showsPrecInner k
          . showChar ' '
          . showsPrecInner c
    where
      showsPrecInner = showsPrec (succ 5)

instance (Show k, Show v) => Show1 (UpdateF k v) where
  liftShowsPrec = undefined

makeFree ''UpdateF

type Update k v = Free (UpdateF k v) ()

instance (Arbitrary k, Arbitrary v) => Arbitrary (Update k v) where
  arbitrary =
    frequency
      [ (1, delete <$> arbitrary),
        (10, insert <$> arbitrary <*> arbitrary),
        (3, adjust <$> (const <$> arbitrary) <*> arbitrary)
      ]