Tutorial by Examples: s

3.0 let string = "My fantastic string" var index = string.startIndex while index != string.endIndex { print(string[index]) index = index.successor() } Note: endIndex is after the end of the string (i.e. string[string.endIndex] is an error, but string[string.startIndex] i...

A defer statement in Go is simply a function call marked to be executed at a later time. Defer statement is an ordinary function call prefixed by the keyword defer. defer someFunction() A deferred function is executed once the function that contains the defer statement returns. Actual call to th...

[1, 2, [[3, 4], [5]], 6].flatten # => [1, 2, 3, 4, 5, 6] If you have a multi-dimensional array and you need to make it a simple (i.e. one-dimensional) array, you can use the #flatten method.

In case you need to read an array elements avoiding repetitions you case use the #uniq method: a = [1, 1, 2, 3, 4, 4, 5] a.uniq #=> [1, 2, 3, 4, 5] Instead, if you want to remove all duplicated elements from an array, you may use #uniq! method: a = [1, 1, 2, 3, 4, 4, 5] a.uniq! #=> [1...

Standard enumerations allow users to declare a useful name for a set of integers. The names are collectively referred to as enumerators. An enumeration and its associated enumerators are defined as follows: enum myEnum { enumName1, enumName2, }; An enumeration is a type, one which is...

A common use for enumerators is for switch statements and so they commonly appear in state machines. In fact a useful feature of switch statements with enumerations is that if no default statement is included for the switch, and not all values of the enum have been utilized, the compiler will issue ...

If targeting Flash Player 11+, the built-in removeChildren method is the best way to remove all children: removeChildren(); //a start and end index can be passed For legacy applications, the same can be accomplished with a loop: while (numChildren > 0) { removeChildAt(0); }

Enums in Swift are much more powerful than some of their counterparts in other languages, such as C. They share many features with classes and structs, such as defining initialisers, computed properties, instance methods, protocol conformances and extensions. protocol ChangesDirection { mutati...

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Using functions that take in and execute closures can be extremely useful for sending a block of code to be executed elsewhere. We can start by allowing our function to take in an optional closure that will (in this case) return Void. func closedFunc(block: (()->Void)? = nil) { print("...

Note: Everything below applies to the str.format method, as well as the format function. In the text below, the two are interchangeable. For every value which is passed to the format function, Python looks for a __format__ method for that argument. Your own custom class can therefore have th...

// RawRepresentable has an associatedType RawValue. // For this struct, we will make the compiler infer the type // by implementing the rawValue variable with a type of String // // Compiler infers RawValue = String without needing typealias // struct NotificationName: RawRepresentable { ...

A protocol may specify that only a class can implement it through using the class keyword in its inheritance list. This keyword must appear before any other inherited protocols in this list. protocol ClassOnlyProtocol: class, SomeOtherProtocol { // Protocol requirements } If a non-class typ...

3.0 Swift 3 introduces the CountedSet class (it's the Swift version of the NSCountedSet Objective-C class). CountedSet, as suggested by the name, keeps track of how many times a value is present. let countedSet = CountedSet() countedSet.add(1) countedSet.add(1) countedSet.add(1) countedSet.a...

Select the .xcdatamodeld file. You will notice you have no 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 for you to work with on the project. In this step there are ...

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 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...