Tutorial by Examples: ed

added in GHC 7.8. OverloadedLists, similar to OverloadedStrings, allows list literals to be desugared as follows: [] -- fromListN 0 [] [x] -- fromListN 1 (x : []) [x .. ] -- fromList (enumFrom x) This comes handy when dealing with types such as Set, Vector and Maps. ['0'...

You can rescue a RecordNotFound exception with a redirect instead of showing an error page: class ApplicationController < ActionController::Base # your other stuff rescue_from ActiveRecord::RecordNotFound do |exception| redirect_to root_path, 404, alert: I18n.t("errors.record...

The following examples can be tested on https://ellie-app.com/m9vmQ8NcMc/0. import Html exposing (..) import Json.Decode payload = """ [ { "bark": true, "tag": "dog", "name": "Zap", "playful": true } , { "w...

First it is important to understand that the Core Data Model is the *.xcdatamodeld file. You will notice you have not entities. You will have to create one yourself. At the bottom of Xcode you will notice a button that says "Add Entity" click it and you will have a new entity in the ...

Relationships are relationship between entities that can be one-to-one or one-to-many. Creating a relationship is not needed to use Core Data.

System.Threading.Timer - Simplest multithreaded timer. Contains two methods and one constructor. Example: A timer calls the DataWrite method, which writes "multithread executed..." after five seconds have elapsed, and then every second after that until the user presses Enter: using Sys...

DROP PROCEDURE if exists displayNext100WithName; DELIMITER $$ CREATE PROCEDURE displayNext100WithName ( nStart int, tblName varchar(100) ) BEGIN DECLARE thesql varchar(500); -- holds the constructed sql string to execute -- expands the sizing of the output buffer to accomoda...

Often times, responsive web design involves media queries, which are CSS blocks that are only executed if a condition is satisfied. This is useful for responsive web design because you can use media queries to specify different CSS styles for the mobile version of your website versus the desktop ver...

There are two ways to define functions with multiple parameters in F#, Curried functions and Tupled functions. let curriedAdd x y = x + y // Signature: x:int -> y:int -> int let tupledAdd (x, y) = x + y // Signature: x:int * y:int -> int All functions defined from outside F# (such as ...

Controlled form components are defined with a value property. The value of controlled inputs is managed by React, user inputs will not have any direct influence on the rendered input. Instead, a change to the value property needs to reflect this change. class Form extends React.Component { con...

Uncontrolled components are inputs that do not have a value property. In opposite to controlled components, it is the application's responsibility to keep the component state and the input value in sync. class Form extends React.Component { constructor(props) { super(props); th...

generate sample data frames: In [57]: df3 = pd.DataFrame({'col1':[211,212,213], 'col2': [221,222,223]}) In [58]: df1 = pd.DataFrame({'col1':[11,12,13], 'col2': [21,22,23]}) In [59]: df2 = pd.DataFrame({'col1':[111,112,113], 'col2': [121,122,123]}) In [60]: df3 = pd.DataFrame({'col1':[211,2...

The pattern matching library trivia provides a system trivia.ppcre that allows captured groups to be bound through pattern matching (trivia:match "John Doe" ((trivia.ppcre:ppcre "(.*)\\W+(.*)" first-name last-name) (list :first-name first-name :last-name last-name))) ;...

wget http://download.redis.io/redis-stable.tar.gz tar xvzf redis-stable.tar.gz cd redis-stable make

redis-server

redis-cli ping This should return PONG

The HTML attribute contenteditable provides a simple way to turn a HTML element into a user-editable area <div contenteditable>You can <b>edit</b> me!</div> Native Rich-Text editing Using JavaScript and execCommandW3C you can additionally pass more editing features to th...

This book is known as CLtL2. This is the second edition of the book Common Lisp the Language. It was published in 1990, before the ANSI CL standard was final. It took the original language definition from the first edition (published in 1984) and described all changes in the standardization process...

On CLiki, a Wiki for Common Lisp and free Common Lisp software, a list of Proposed ANSI Revisions and Clarifications is being maintained. Since the Common Lisp standard has not changed since 1994, users have found several problems with the specification document. These are documented on the CLiki p...

When to use An attached property is a dependency property that can be applied to any DependencyObject to enhance the behavior of various controls or services that are aware of the property's existence. Some use cases for attached properties include: Having a parent element iterate through its c...