kana-sama

{-# LANGUAGE ConstraintKinds       #-}
{-# LANGUAGE DataKinds             #-}
{-# LANGUAGE DeriveDataTypeable    #-}
{-# LANGUAGE DeriveFunctor         #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE FlexibleInstances     #-}
{-# LANGUAGE GADTs                 #-}
{-# LANGUAGE KindSignatures        #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE RankNTypes            #-}

kana-sama

Книги

• Structure and Interpretation of Computer Programs
• Write Yourself a Scheme in 48 Hours / Write You A Scheme, Version 2
• http://komar.bitcheese.net/files/учебник-по-теории-категорий.pdf
• Algebra: Chapter 0
• Category Theory for Programmers
• Топосы - категорный анализ логики
• DEPENDENT TYPES IN HASKELL: THEORY AND PRACTICE
• Category Theory for Computing Science

cdepillabout

# This file is an example of overriding a GHC core Haskell library (like
# bytestring, containers, text, unix, etc) when building a Haskell package.

let default-nixpkgs =
      builtins.fetchTarball {
        # nixpkgs haskell-updates branch as of 2019/09/15.
        url = "https://github.com/NixOS/nixpkgs/archive/a51b3367ab6acc72630da0bad50ce14fa86996d0.tar.gz";
        sha256 = "05d3jxxk5dxzs9b3nan16lhkrjnzf0bjd4xy66az86fsafnrr9rd";
      };
in

kana-sama

{-# LANGUAGE DeriveFunctor #-}
{-# LANGUAGE RankNTypes #-}

module Main where

import Data.Functor.Const
import Data.Functor.Identity (Identity (..))
import Data.Monoid

data Profile = Profile {user :: User}

kana-sama

lens :: (s -> a) -> (s -> b -> t) -> Lens s t a b
lens get set next value = fmap (set value) . next . get $ value

-- | A lens focusing on the first element in a pair
_1 :: Lens (a, x) (b, x) a b
_1 = lens fst (\(_, b) a -> (a, b))

-- | A lens focusing on the second element in a pair
_2 :: Lens (x, a) (x, b) a b
_2 = lens snd (\(a, _) b -> (a, b))