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{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Util.IdGen where
import Control.Monad.Fix
import Control.Monad.Trans.State.Strict
newtype IdGen a = IdGen (State Int a)
deriving newtype (Functor, Applicative, Monad, MonadFix)
genId :: IdGen Int
genId = IdGen (state (\i -> (i, i + 1)))
runIdGen :: Int -> IdGen a -> a
runIdGen start (IdGen m) = evalState m start
runIdGen' :: Int -> IdGen a -> (a, Int)
runIdGen' start (IdGen m) = runState m start
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