Tutorial by Examples

An SSH key has two pieces, the public key and the private key. The private key: Is usually in a file named id_rsa, but it can be given any name. CANNOT BE REGENERATED IF LOST!!!! Do not lose this file! If you lose it, you will not be able to get back into your instance. (StackOverflow is li...

A Semantic Model offers a deeper level of interpretation and insight of code compare to a syntax tree. Where syntax trees can tell the names of variables, semantic models also give the type and all references. Syntax trees notice method calls, but semantic models give references to the precise locat...

In the root of your ionic app, there is a gulpfile.js file. Open it in an editor and paste the following gulp task: gulp.task('lint', function() { return gulp.src(['./www/js/**/*.js']) .pipe(jshint('.jshintrc')) .pipe(jshint.reporter('jshint-stylish')) .pipe(jshint...

Create a file named '.jshintrc' in the root of your app, where package.json is. *Note on windows: create a file named "jshintrc.txt". Then rename it to ".jshintrc." (notice the dot at the end). This is a configuration file. It can for example tell jshint to ignore certain varia...

Create a file named: "Makefile" (with no extension) in the root of your app Open it in a text editor and add this: android: gulp lint gulp sass ionic run android --device ios: gulp lint gulp sass ionic build ios This will lint your app and ...

FRP, or Functional Reactive Programming, has some basic terms which you need to know. Every piece of data can be represented as Observable, which is an asynchronous data stream. The power of FRP is in representation synchronous and asynchronous events as streams, Observables, and providing the same...

RxSwift offers many ways to create an Observable, let's take a look: import RxSwift let intObservale = Observable.just(123) // Observable<Int> let stringObservale = Observable.just("RxSwift") // Observable<String> let doubleObservale = Observable.just(3.14) // Observable&...

After the subscription was created, it is important to manage its correct deallocation. The docs told us that If a sequence terminates in finite time, not calling dispose or not using addDisposableTo(disposeBag) won't cause any permanent resource leaks. However, those resources will be used unti...

Denotes a signed integer type with "the natural size suggested by the architecture of the execution environment", whose range includes at least -32767 to +32767, inclusive. int x = 2; int y = 3; int z = x + y; Can be combined with unsigned, short, long, and long long (q.v.) in order...

You can restart ubuntu from command line. Below is example of restarting ubuntu immediately. sudo reboot You need to have sudo privilege in order to use this command. Another commands with same results are sudo shutdown -r now and sudo init 6.

In some places in Common Lisp, a series of forms are evaluated in order. For instance, in the body of a defun or lambda, or the body of a dotimes. In those cases, writing multiple forms in order works as expected. In a few places, however, such as the then and else parts of an if expressions, onl...

The general purpose special operator progn is used for evaluating zero or more forms. The value of the last form is returned. For instance, in the following, (print 'hello) is evaluated (and its result is ignored), and then 42 is evaluated and its result (42) is returned: (progn (print 'hello...

Often times, it is helpful to evaluate multiple expressions and to return the result from the first or second form rather than the last. This is easy to accomplish using let and, for instance: (let ((form1-result form1)) form2 form3 ;; ... form-n-1 form-n form1-result) Because...

The special operator block allows grouping of several Lisp forms (like an implicit progn) and it also takes a name to name the block. When the forms within the block are evaluated, the special operator return-from can be used to leave the block. For instance: (block foo (print 'hello) ; e...

For lots of control in a group forms, the tagbody special operator can be very helpful. The forms inside a tagbody form are either go tags (which are just symbols or integers) or forms to execute. Within a tagbody, the go special operator is used to transfer execution to a new location. This type...

When writing macros that expand into forms that might involve grouping, it is worthwhile spending some time considering what grouping construction to expand into. For definition style forms, for instance, a define-widget macro that will usually appear as a top-level form, and that several defuns, d...

You can use npm install -g to install a package "globally." This is typically done to install an executable that you can add to your path to run. For example: npm install -g gulp-cli If you update your path, you can call gulp directly. On many OSes, npm install -g will attempt to writ...

Node Version Manager (nvm) greatly simplifies the management of Node.js versions, their installation, and removes the need for sudo when dealing with packages (e.g. npm install ...). Fish Shell (fish) "is a smart and user-friendly command line shell for OS X, Linux, and the rest of the family&...

Square Root Use Math.sqrt() to find the square root of a number Math.sqrt(16) #=> 4 Cube Root To find the cube root of a number, use the Math.cbrt() function 6 Math.cbrt(27) #=> 3 Finding nth-roots To find the nth-root, use the Math.pow() function and pass in a fractional expo...

This is a custom JAX-RS @Provider to use Gson as the JSON parser. The example also shows how to use custom Java 8 date/time converters. @Provider @Produces(MediaType.APPLICATION_JSON) @Consumes(MediaType.APPLICATION_JSON) public class JerseyServerGson implements MessageBodyWriter<O...