module Data.List.Utils where

import Data.Semiring ((+))
import Data.Ord (class Ord, compare)
import Data.Eq (class Eq, eq)

data Label a b = Label a b

genLabels :: forall a. [a] -> [Label a Integer]
genLabels = genLabels' 0
  where genLabels' _ []     = []
        genLabels' n [x|xs] = [Label x n|genLabels' (n + 1) xs]

removeLabel :: forall a b. Label a b -> a
removeLabel (Label a _) = a

removeLabels :: forall a b. [Label a b] -> [a]
removeLabels [] = []
removeLabels [x|xs] = [removeLabel x|removeLabels xs]

instance Eq b => Eq (Label a b) where
  eq (Label _ a) (Label _ b) = eq a b

instance Ord b => Ord (Label a b) where
  compare (Label _ a) (Label _ b) = compare a b