data-diverse-0.1.0.0: src/Data/Diverse/Reduce.hs

{-# LANGUAGE DataKinds #-}
{-# LANGUAGE KindSignatures #-}
{-# LANGUAGE MultiParamTypeClasses #-}

module Data.Diverse.Reduce where

import Data.Kind

-- | Reduce a polymorphic variant @v xs@ into @r@ using handlers.
-- This class is required in order to step through all the different types in a variant.
class Reduce v handler (xs :: [Type]) r where
    reduce :: handler xs r -> v xs -> r