-- |
-- Module: Data.IntSet.Optics
-- Description: Optics for working with 'IntSet's.
--
-- This module defines optics for constructing and manipulating finite 'IntSet's.
--
module Data.IntSet.Optics
  ( members
  , setmapped
  , setOf
  ) where

import Data.IntSet (IntSet)
import qualified Data.IntSet as IntSet

import Optics.Fold
import Optics.Optic
import Optics.Setter

-- | IntSet isn't Foldable, but this 'Fold' can be used to access the members of
-- an 'IntSet'.
--
-- >>> sumOf members $ setOf folded [1,2,3,4]
-- 10
members :: Fold IntSet Int
members :: Fold IntSet Int
members = (IntSet -> [Int]) -> Fold IntSet Int
forall (f :: * -> *) s a. Foldable f => (s -> f a) -> Fold s a
folding IntSet -> [Int]
IntSet.toAscList
{-# INLINE members #-}

-- | This 'Setter' can be used to change the type of a 'IntSet' by mapping the
-- elements to new values.
--
-- Sadly, you can't create a valid 'Optics.Traversal.Traversal' for an 'IntSet',
-- but you can manipulate it by reading using 'Optics.Fold.folded' and
-- reindexing it via 'setmapped'.
--
-- >>> over setmapped (+1) (IntSet.fromList [1,2,3,4])
-- fromList [2,3,4,5]
setmapped :: Setter' IntSet Int
setmapped :: Setter' IntSet Int
setmapped = ((Int -> Int) -> IntSet -> IntSet) -> Setter' IntSet Int
forall a b s t. ((a -> b) -> s -> t) -> Setter s t a b
sets (Int -> Int) -> IntSet -> IntSet
IntSet.map
{-# INLINE setmapped #-}

-- | Construct an 'IntSet' from a fold.
--
-- >>> setOf folded [1,2,3,4]
-- fromList [1,2,3,4]
--
-- >>> setOf (folded % _2) [("hello",1),("world",2),("!!!",3)]
-- fromList [1,2,3]
setOf :: Is k A_Fold => Optic' k is s Int -> s -> IntSet
setOf :: Optic' k is s Int -> s -> IntSet
setOf Optic' k is s Int
l = Optic' k is s Int -> (Int -> IntSet) -> s -> IntSet
forall k m (is :: IxList) s a.
(Is k A_Fold, Monoid m) =>
Optic' k is s a -> (a -> m) -> s -> m
foldMapOf Optic' k is s Int
l Int -> IntSet
IntSet.singleton
{-# INLINE setOf #-}

-- $setup
-- >>> import Optics.Core