Arbitrary for custom ADT

Main.purs

module Main where

import Prelude
import Effect (Effect)
import Effect.Class.Console as Console
import Data.Generic.Rep (class Generic)
import Data.Show.Generic as Show.Generic
import Test.QuickCheck.Arbitrary (class Arbitrary)
import Test.QuickCheck.Arbitrary as Arbitrary
import Test.QuickCheck.Gen (Gen)
import Test.QuickCheck.Gen as Gen

data FooBarBaz a b c
  = Foo a
  | Bar b
  | Baz c
  
derive instance Generic (FooBarBaz a b c) _

instance (Show a, Show b, Show c) => Show (FooBarBaz a b c) where
  show = Show.Generic.genericShow

instance (Arbitrary a, Arbitrary b, Arbitrary c) => Arbitrary (FooBarBaz a b c) where
  arbitrary = Arbitrary.genericArbitrary

main :: Effect Unit
main = do
  sample <- Gen.randomSample (Arbitrary.arbitrary :: Gen (FooBarBaz Number String Int))
  Console.logShow sample