pthariensflame

The Indexed State Monad in Haskell, Scala, and C#

Have you ever had to write code that made a complex series of succesive modifications to a single piece of mutable state? (Almost certainly yes.)

Did you ever wish you could make the compiler tell you if a particular operation on the state was illegal at a given point in the modifications? (If you're a fan of static typing, probably yes.)

If that's the case, the indexed state monad can help!

Motivation

ekantola

/*
 * Observable
 */

var xs = Rx.Observable.range(0, 3)
xs.subscribe(log)
//=> 0
//=> 1
//=> 2

charleslouis

<?php

/**
 * [list_searcheable_acf list all the custom fields we want to include in our search query]
 * @return [array] [list of custom fields]
 */
function list_searcheable_acf(){
  $list_searcheable_acf = array("title", "sub_title", "excerpt_short", "excerpt_long", "xyz", "myACF");
  return $list_searcheable_acf;
}

patocallaghan

##Chai Expect

##Language Chains

• to
• be
• been
• is
• that
• and
• have

chill117

#!/bin/bash

#
# 	Use this script to perform backups of one or more MySQL databases.
#

# Databases that you wish to be backed up by this script. You can have any number of databases specified; encapsilate each database name in single quotes and separate each database name by a space.
#
# Example:
# databases=( '__DATABASE_1__' '__DATABASE_2__' )

evansb

{-# LANGUAGE InstanceSigs #-}

import Control.Applicative
import Control.Monad
import Control.Monad.Trans.Writer
-- Here is a direct style pythagoras function
-- There are two noticeable things in the function body.
-- 1. Evaluation order of x * x vs y * y is unknown/implicit.
-- 2. We don't care what happens to the final value (implicit continuation).
pyth :: (Floating a) => a -> a -> a

CMCDragonkai

import Control.Concurrent.MVar

type Channel a = (ReadPort a, WritePort a)
type ReadPort a = MVar (Stream a)
type WritePort a = MVar (Stream a)
type Stream a = MVar (Item a)
data Item a = MkItem a (Stream a)

newChan :: IO (Channel a)
newChan = do

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

kosmikus

{-# LANGUAGE DataKinds, PolyKinds, TypeOperators #-}
{-# LANGUAGE TypeFamilies, FlexibleInstances, ScopedTypeVariables #-}
{-# LANGUAGE InstanceSigs #-}

module TinyServant where

import Control.Applicative
import GHC.TypeLits
import Text.Read
import Data.Time

llelf

{-# LANGUAGE GADTs, ConstraintKinds, Rank2Types, ImplicitParams #-}

data Rec fields where
  Rec :: fields => Rec fields

infixr 1 ?
(?) :: Rec fields -> (fields => r) -> r
Rec ? e = e

record :: Rec (?a :: Int, ?b :: String)