masaeedu

// This gist shows how to factor a concrete stateful fold in vanilla JS
// into a number of general purpose utilities that can be combined to recover
// the original behavior

// We're going to start from a particular code snippet and iteratively make
// small changes to it to get a finished product

// While reading this post, it is useful to have a diff tool at hand that allows
// you to compare snippets side by side and see what changed in each iteration

masaeedu

const { adt, match, otherwise } = require("@masaeedu/adt");
const {
  Obj,
  Fn,
  Arr,
  Cont,
  implement,
  Functor,
  Apply,
  Chain,

masaeedu

:: :: morphism c = c -> c -> *

:: :: morphism c -> *
:: category p =
::   { id: p a a, compose: p b c -> p a b -> p a c }

:: :: (c -> d) -> morphism c -> morphism d -> *
:: functor f i o =
::   { map: i a b -> o (f a) (f b) }

masaeedu

{-# LANGUAGE FlexibleContexts           #-}
{-# LANGUAGE ScopedTypeVariables        #-}
{-# LANGUAGE ViewPatterns               #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE FlexibleInstances          #-}
{-# LANGUAGE MultiParamTypeClasses      #-}

module Main where

import Prelude as P

masaeedu

{-# LANGUAGE
    RankNTypes,
    TypeApplications,
    TypeOperators,
    KindSignatures,
    TypeFamilies,
    TypeInType,
    MultiParamTypeClasses,
    FunctionalDependencies,
    FlexibleInstances,

masaeedu

{-# LANGUAGE
    KindSignatures
  , DataKinds
  , RankNTypes
  , GADTs
  , TypeFamilies
  , TypeFamilyDependencies
  , ScopedTypeVariables
  , TypeApplications
  , ViewPatterns

masaeedu

module Test where

import Prelude

import Data.Lens (Lens, _Just, lens, (.~))
import Data.Maybe (Maybe(..))
import Effect.Exception.Unsafe (unsafeThrow)

data CRUD a
  = Create

masaeedu

module ComonadKleisli where

import Data.Maybe
import Data.List
import Control.Monad

fmapM :: (a -> Maybe b) -> [a] -> Maybe [b]
fmapM f = Just . catMaybes . fmap f

duplicateM :: [a] -> Maybe [[a]]

masaeedu

#!/usr/bin/env bash
set -Eeuxo pipefail

# Set up git
git init
gitignore haskell
echo '*.cabal' >> .gitignore

# Set up niv
niv init

masaeedu

{-# LANGUAGE
    TypeOperators
  , RankNTypes
  , MultiParamTypeClasses
  , ConstraintKinds
  , QuantifiedConstraints
  , KindSignatures
#-}

module Main where