Tutorial by Examples: i

With Gson, you can read JSON dataset and map them to a custom class MyClass. Since Gson is not serializable, each executor needs its own Gson object. Also, MyClass must be serializable in order to pass it between executors. Note that the file(s) that is offered as a json file is not a typical JSON...

We define the type of boolean expressions whose atoms are identified by strings as type expr = | Atom of string | Not of expr | And of expr * expr | Or of expr * expr and can evaluate these expressions using an oracle : string -> bool giving the values of the atoms we find as follows: le...

Pattern matching allows to deconstruct complex values and it is by no way limited to the “outer most” level of the representation of a value. To illustrate this, we implement the function transforming a boolean expression into a boolean expression where all negations are only on atoms, the so calle...

Pattern matching can be used to deconstruct records. We illustrate this with a record type representing locations in a text file, e.g. the source code of a program. type location = { filename : string; line: int; column: int; offset: int; } A value x of type location can be deconstr...

We prepare a file called reverser.ml with the following contents: let acc = ref [] in try while true do acc := read_line () :: !acc; done with End_of_file -> print_string (String.concat "\n" !acc) We then compile our program using ...

The List.fold_left and List.fold_right functions are higher-order functions that implement the outer logic of list aggregation. Aggregating a list, sometimes also referred to as reducing a list, means computing a value derived from the sequential inspection of all items in that list. The documenta...

final TextView mTextView = (TextView) findViewById(R.id.text); ... // Instantiate the RequestQueue. RequestQueue queue = Volley.newRequestQueue(this); String url ="http://www.google.com"; // Request a string response from the provided URL. StringRequest stringRequest = new String...

There are several additional attributes that the Volley NetworkImageView adds to the standard ImageView. However, these attributes can only be set in code. The following is an example of how to make an extension class that will pick up the attributes from your XML layout file and apply them to the N...

In Elm, reducing functions are called "folds", and there are two standard methods to "fold" values up: from the left, foldl, and from the right, foldr. > List.foldl (+) 0 [1,2,3] 6 : number The arguments to foldl and foldr are: reducing function: newValue -> accumul...

A reference to an option &Option<T> cannot be unwrapped if the type T is not copyable. The solution is to change the option to &Option<&T> using as_ref(). Rust forbids transferring of ownership of objects while the objects are borrowed. When the Option itself is borrowed (&a...

Woocommerce is a plugin for WordPress and can be installed like any other WordPress plugin. WooCommerce can only be installed on self hosted installations of WordPress, it cannot be installed onto a site hosted by the wordpress.com service. If you don't have WordPress installed for your website, fo...

A while loop will evaluate its condition, and if true, it will execute the code inside and start over. That is, as long as its condition evaluates to true, the while loop will execute over and over. This loop will execute 100 times, each time adding 1 to the variable num: int num = 0; while (nu...

A do while loop is the same as a while loop, except that it is guaranteed to execute at least one time. The following loop will execute 100 times. int i = 0; do { i++; } while (i < 100); A similar loop, but with a different condition, will execute 1 time. int i = 0; do { i++; ...

To remove a specific item from the browser Storage (the opposite of setItem) use removeItem localStorage.removeItem("greet"); Example: localStorage.setItem("greet", "hi"); localStorage.removeItem("greet"); console.log( localStorage.getItem("greet...

localStorage, sessionStorage are JavaScript Objects and you can treat them as such. Instead of using Storage Methods like .getItem(), .setItem(), etc… here's a simpler alternative: // Set localStorage.greet = "Hi!"; // Same as: window.localStorage.setItem("greet", "Hi!&qu...

Type casting is done with either the as operator: var chair:Chair = furniture as Chair; Or by wrapping the value in Type(): var chair:Chair = Chair(furniture); If the cast fails with as, the result of that cast is null. If the cast fails by wrapping in Type(), a TypeError is thrown.

Functions are of the type Function: function example():void { } trace(example is Function); // true They can be referenced by other variables with the type Function: var ref:Function = example; ref(); // ref.call(), ref.apply(), etc. And they can be passed in as arguments for parameters wh...

You can tell the compiler the type of a value by annotating it with :Type: var value:int = 10; // A property "value" of type "int". Function parameters and return types can also be annotated: // This function accepts two ints and returns an int. function sum(a:int, b:int):i...

You can use the is operator to validate whether a value is of a certain type: var sprite:Sprite = new Sprite(); trace(sprite is Sprite); // true trace(sprite is DisplayObject); // true, Sprite inherits DisplayObject trace(sprite is IBitmapDrawable); // true, DisplayObject implements IBitmapDra...

The C++ approach - new and delete In a language like C++, the application program is responsible for managing the memory used by dynamically allocated memory. When an object is created in the C++ heap using the new operator, there needs to be a corresponding use of the delete operator to dispose o...