Lev135

Benchmark bench-trans-speed: RUNNING...
benchmarking 1/20 modify/pure/2000
time                 1.033 μs   (1.022 μs .. 1.052 μs)
                     0.991 R²   (0.981 R² .. 0.997 R²)
mean                 1.130 μs   (1.084 μs .. 1.207 μs)
std dev              182.7 ns   (129.1 ns .. 265.3 ns)
variance introduced by outliers: 95% (severely inflated)

benchmarking 1/20 modify/ParserT State/2000
time                 1.250 μs   (1.236 μs .. 1.264 μs)

Lev135

{-# OPTIONS_GHC -Wall  #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleInstances #-}

import Control.Monad
import Data.Bifunctor

type AnOptic p s t a b = p a b -> p s t

Lev135

Writing profunctor optics by the same template

All of the profunctor optics kind have the same, very simple, pattern:

type AnOptic p s t a b = p a b -> p s t
type Optic c s t a b = forall p. c p => AnOptic p s t a b

type Iso s t a b = Optic Profunctor s t a b

Lev135

{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE InstanceSigs #-}