constructor-names.purs

module Main where

import Prelude

import Data.Generic.Rep
import Type.Proxy
import Data.Symbol (SProxy(..), reflectSymbol, class IsSymbol)
import Type.Equality
import Control.Alternative
import Control.Monad.Eff.Console (logShow)
import TryPureScript

class ConstructorNames a where
  names :: forall f. Alternative f => Proxy a -> f String

instance namesSum :: (ConstructorNames a, ConstructorNames b) => ConstructorNames (Sum a b) where
  names _ = names (Proxy :: Proxy a) <|> names (Proxy :: Proxy b)
  
instance namesConstructor :: (TypeEquals tail (Argument a), IsSymbol name) => ConstructorNames (Constructor name tail) where
  names _ = pure (reflectSymbol (SProxy :: SProxy name))
  
instance namesNoConstructors :: ConstructorNames NoArguments where
  names _ = empty
  
data Test = Bar Int | Baz String

derive instance genericTest :: Generic Test _

toRep :: forall from to. Generic from to => Proxy from -> Proxy to
toRep _ = Proxy

testNames :: Array String
testNames = names (toRep (Proxy :: Proxy Test))

main = render =<< withConsole (logShow testNames)