Tutorial by Examples: p

An input port can be created in many ways, but usually the method starts with open-input-. String port You can use a string as a port using open-input-string. It will create a port that will be able to read from the string. (define p (open-input-string "(a . (b . (c . ()))) 34")) ...

Reading from an input port can be done in many ways. We can use the read method used by the REPL. It will read and interpret space separated expressions. Taking the example from the string port above. We can read from the port like this: (define p (open-input-string "(a . (b . (c . ()))) 3...

import pyglet audio = pyglet.media.load("audio.wav") audio.play() For further information, see pyglet

There is a particular syntax that allow us to write cons cell in a more compact way than using the cons constructor. A pair can be written as such: '(1 . 2) == (cons 1 2) The big difference is that we can create pairs using quote. Otherwise, Scheme would create a proper list (1 . (2 . '())). T...

A pair can be create with the cons function. The name of the function stand for constructor. In Scheme, everything is pretty much based on pairs. (cons a b) The function return a pair containing the element a and b. The first parameter of cons is called car (Content Address Register) and the sec...

The data in the pair can be accessed with utility functions. To access the car, we have to use the car function. (car (cons a b)) > a Also we can verify the following equality: (eq? a (car (cons a b))) > #t

To access the cdr, we have to use the cdr function. (cdr (cons a b)) b Also we can verify the following equality: (eq? b (cdr (cons a b))) #t

List in scheme are nothing else than a series of pairs nested in each other in the cdr of a cons. And the last cdr of a proper list is the empty list '(). To create the list (1 2 3 4), we'd have something like this: (cons 4 '()) > (4) (cons 3 (cons 4 '())) > (3 4) (cons 2 (cons 3 (cons 4...

A enum declares a set of ordered values - the typedef just adds a handy name to this. The 1st element is 0 etc. typedef enum { Monday=1, Tuesday, Wednesday } WORKDAYS; WORKDAYS today = Monday;//value 1

Here’s an example vector asset which we’re actually using in AppCompat: res/drawable/ic_search.xml <vector xmlns:android="..." android:width="24dp" android:height="24dp" android:viewportWidth="24.0" android:viewportHeig...

Here is a simple VectorDrawable in this vectordrawable.xml file. <vector xmlns:android="http://schemas.android.com/apk/res/android" android:height="64dp" android:width="64dp" android:viewportHeight="600" android:viewportWidth=&quot...

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This is for those moving to data.table >= 1.9.8 You have a data set of pet owners and names, but you suspect some repeated data has been captured. library(data.table) DT <- data.table(pet = c("dog","dog","cat","dog"), owner = c(&quot...

SQL Server 2012 / 2014 DECLARE @RowsPerPage INT = 10, @PageNumber INT = 4 SELECT OrderId, ProductId FROM OrderDetail ORDER BY OrderId OFFSET (@PageNumber - 1) * @RowsPerPage ROWS FETCH NEXT @RowsPerPage ROWS ONLY SQL Server 2005/2008/R2 DECLARE @RowsPerPage INT = 10, @PageNumber INT = ...

Firebase Cloud Messaging is the Firebase service that handles push notifications. You can add this service in any client: web, Android or IOS. The specific functioning for each must be read from the documentation. For adding FCM in any type of project, is always adding a library. Considering the s...

Dependenct Injection Intro An application is composed of many objects that collaborate with each other. Objects usually depend on other objects to perform some task. When an object is responsible for referencing its own dependencies it leads to a highly coupled, hard-to-test and hard-to-change code...

This example will demonstrate how to use Dependency Injection (DI) design pattern in Swift using these methods: Initializer Injection (the proper term is Constructor Injection, but since Swift has initializers it's called initializer injection) Property Injection Method Injection Example Set...

Let's say we have a form like the one below. We want to send the data to our webserver via AJAX and from there to a script running on an external server. So we have normal inputs, a multi-select field and a file dropzone where we can upload multiple files. Assuming the AJAX POST request was succ...

Introduction NMAKE is a command-line utility developed by Microsoft to be used primarily in conjunction with Microsoft Visual Studio and/or the Visual C++ command line tools. NMAKE is build system that falls under the Make family of build systems, but has certain distinct features that diverge fro...

Maybe Maybe is an applicative functor containing a possibly-absent value. instance Applicative Maybe where pure = Just Just f <*> Just x = Just $ f x _ <*> _ = Nothing pure lifts the given value into Maybe by applying Just to it. The (<*>) function applies...