davidchase

module Reader exposing
  ( return
  , ask
  , runReader
  , local
  , fmap
  , chain
  )

type Reader r a = Reader (r -> a)

davidchase

https://flems.io/#0=N4IgZglgNgpgziAXAbVAOwIYFsZJAOgAsAXLKEAGhAGMB7NYmBvAHhLID4AdNNmDACbc0AAhEs41AE4QADsRFwp1ALxcQJYrLiIA9LoCuaWQGsA5vjpZDaCPQC0xAJ6yYAAQAM+ACz4AjLoCEHDENnZoji4w+ABWcOocLLqSMvLCYkmE-EI8GQBGtAJO6eK6BUXCmaRQHJQgcDCw1MThCIggAEyIAGwAHCAAvhTo2LjtUBB5sQhUdAxMxHgQWLK0UgrAIlJMAjBSIgMiYFK0WCIA5JraejamFla67Lqy2xjNycQYaAIYUPTRWEKBlg03OPB4MAAHqt1kcjM1wkcTlgAKIANwWAApnK4KCJGjAcAwAJQiYC5LYwYgGKSiMDwlr0TFoKHEUnk0RifGwInEfCCATohYAGWCjBZUmxUTxLMhbIpAx4irQEOhawU9LQCPoIiwGFkmLAeKU1HZFO21NpcK1jLQzNZZs5YhNmLRvxEKg4IllxENrt+xMDCqV4NlMI1DMRnwNkLxYEdYjAmMhxPNVJpokhIZVYfV1u1ohwUjMMGTcATlMtdMjTJ9FbEkLg+G2AgM1FL0ZlDuDaGVqvD+dtRyp1EIQoYmJpUArFozg-C9rl9eHxFHk6k04pXJE+GIWTt2zgsg9XsPsmmTKDTq5u-3i-l17Elgwq8I99TnOVfdzsM1BaOtBQAIBpgGgeIQLYLS-MaygzumVp-kO75kluIiwAobzUB6IgQRAUFQKhPqYphH7bi6iELmiy5iJh2GgcR1DUHiVGoWIREkahAykQc2b9nmFE6ts3x7AAIgA8gAspiJrMRAMAAO54o0WBwVW861g6KHXuRNZ2j8nzUd6rKYkJuySmicnyZi+kYMSSlQCp3FiFxPbflCA5zCEOECNhkIniIWY5u5eaeRhUDyRgThwNhGD+Xk-kYKGwW-rpWxGNJsFac6yiYhAAgfm5aopTaiIhBg6wAOp4W+saKJlHJiLOCG6chDVckRKaoS

davidchase

// how would you programmatically create a list of 3 elements and set to the DOM
// the data should come from a external entity like a third party source ie https://reqres.in/api/users
/*
    should result into
    <ul>
      <li>1</li>
      <li>2</li>
      <li>3</li>
    </ul>
*/

davidchase

module Main where

import Prelude

import Control.Monad.Eff (Eff)
import Data.Foldable (fold)
import TryPureScript (DOM, p, render, text)

data Maybe a = Just a | Nothing

davidchase

const obj = { 1: {}, 2: {}, 3: {} }

const calculateLimitedPermutation = (pFn , aFn, o) => {
   const recurse = (index = 0, xs = []) => {
     const arr = Object.keys(o)
     if ( arr.length === 0 ) return o;
     const types = arr.reduce(
       (acc, key, idx) =>
       idx === index
       ? { ...acc, ...{ [key]: pFn(key) } }

davidchase

Bare Bones Object Based MultiMap

use case finding duplicates

davidchase

const toString = buff => buff.toString()
const jParse = str => JSON.parse(str)
const stringify = obj => JSON.stringify(obj)
const keys = obj => Object.keys(obj)
const dissoc = (str, obj) => 
   keys(obj).reduce((acc, k) => k !== str ? (acc[k] = obj[k], acc) : acc , {})


const simpleReq = (url, opts = {}) => 
  new Promise((resolve, reject) => {

davidchase

// Array#reduce + recursion to flatten
// any level of nested arrays

// So we reduce the nested array and aggregate the values of the Integer type into the seed array
// during the aggregation we 1st check if the values from the input array are of the Array type via `isArray`
// if so we call the function `flatten` again passing that array value as input and if the value is 
// not of the Array type it we `concat` the value with the seed array
// below is a timeline of how the values look after the input array is given
// [[1, 2, [3]], 4]: --- [1,2,[3]] --> 1 --> 2 --> [3] --> 3 --> 4 
const flatten = array => array.reduce((acc, val) => acc.concat(Array.isArray(x) ? flatten(val) : val), [])

davidchase

const Coyo = (f, v) => ({fn: f, val: v})

const id = x => x

const liftCoyo = a => Coyo(id, a)

const fmap = (fn, coyo) => Coyo(compose(fn, coyo.fn), coyo.val)

const lower = coyo => map(coyo.fn, coyo.val)

davidchase

// @TODO pull out the mapping and filtering
// make composable/lazy(only run when fold'ing)
const copyList = xs => reduce(concat, [], xs)
const filterR = (f, xs) => reduce((acc, x) => f(x) ? acc.concat(x) : acc , [], xs)
const mapR = (f, xs) => reduce((acc, x) => acc.concat(f(x)), [], xs)

// List with methods in terms of reduce
const List = xs => ({
  xs,
  map: f => List(mapR(f, xs)),