Tutorial by Examples: n

The type of the literal Prelude> :t 1 1 :: Num a => a choosing a concrete type with annotations You can specify the type as long as the target type is Num with an annotation: Prelude> 1 :: Int 1 it :: Int Prelude> 1 :: Double 1.0 it :: Double Prelude> 1 :: Word 1 it :: ...

The type of the literal Prelude> :t 1.0 1.0 :: Fractional a => a Choosing a concrete type with annotations You can specify the type with a type annotation. The only requirement is that the type must have a Fractional instance. Prelude> 1.0 :: Double 1.0 it :: Double Prelude> 1....

#include <stdio.h> #include <stdlib.h> #include <string.h> int main(int argc, char **argv) { /* Exit if no second argument is found. */ if (argc != 2) { puts("Argument missing."); return EXIT_FAILURE; } size_t len = str...

Sets are unordered collections of unique values. Unique values must be of the same type. var colors = Set<String>() You can declare a set with values by using the array literal syntax. var favoriteColors: Set<String> = ["Red", "Blue", "Green", "Blu...

To access the event object, include an event parameter in the event listener callback function: var foo = document.getElementById("foo"); foo.addEventListener("click", onClick); function onClick(event) { // the `event` parameter is the event object // e.g. `event.type`...

println! (and its sibling, print!) provides a convenient mechanism for producing and printing text that contains dynamic data, similar to the printf family of functions found in many other languages. Its first argument is a format string, which dictates how the other arguments should be printed as t...

A simple function that does not accept any parameters and does not return any values: func SayHello() { fmt.Println("Hello!") }

A function can return one or more values to the caller: func AddAndMultiply(a, b int) (int, int) { return a+b, a*b } The second return value can also be the error var : import errors func Divide(dividend, divisor int) (int, error) { if divisor == 0 { return 0, errors.New(...

Return values can be assigned to a local variable. An empty return statement can then be used to return their current values. This is known as "naked" return. Naked return statements should be used only in short functions as they harm readability in longer functions: func Inverse(v float3...

A basic struct is declared as follows: type User struct { FirstName, LastName string Email string Age int } Each value is called a field. Fields are usually written one per line, with the field's name preceeding its type. Consecutive fields of the sa...

Struct fields whose names begin with an uppercase letter are exported. All other names are unexported. type Account struct { UserID int // exported accessToken string // unexported } Unexported fields can only be accessed by code within the same package. As such, if you are ev...

Composition provides an alternative to inheritance. A struct may include another type by name in its declaration: type Request struct { Resource string } type AuthenticatedRequest struct { Request Username, Password string } In the example above, AuthenticatedRequest will con...

Any function can be invoked as a goroutine by prefixing its invocation with the keyword go: func DoMultiply(x,y int) { // Simulate some hard work time.Sleep(time.Second * 1) fmt.Printf("Result: %d\n", x * y) } go DoMultiply(1,2) // first execution, non-blocking go DoMu...

single channel, single goroutine, one write, one read. package main import "fmt" import "time" func main() { // create new channel of type string ch := make(chan string) // start new anonymous goroutine go func() { time.Sleep(time.Second) ...

The filter() method accepts a test function, and returns a new array containing only the elements of the original array that pass the test provided. // Suppose we want to get all odd number in an array: var numbers = [5, 32, 43, 4]; 5.1 var odd = numbers.filter(function(n) { return n % 2 !=...

PorterDuff.Mode is used to create a PorterDuffColorFilter. A color filter modifies the color of each pixel of a visual resource. ColorFilter filter = new PorterDuffColorFilter(Color.BLUE, PorterDuff.Mode.SRC_IN); The above filter will tint the non-transparent pixels to blue color. The color fil...

An Xfermode (think "transfer" mode) works as a transfer step in drawing pipeline. When an Xfermode is applied to a Paint, the pixels drawn with the paint are combined with underlying pixels (already drawn) as per the mode: paint.setColor(Color.BLUE); paint.setXfermode(new PorterDuffXferm...

In info.plist set View controller-based status bar appearance to YES In view controllers not contained by UINavigationController implement this method. In Objective-C: - (UIStatusBarStyle)preferredStatusBarStyle { return UIStatusBarStyleLightContent; } In Swift: override func pre...

Column aliases are used mainly to shorten code and make column names more readable. Code becomes shorter as long table names and unnecessary identification of columns (e.g., there may be 2 IDs in the table, but only one is used in the statement) can be avoided. Along with table aliases this allows ...

A simple literal function, printing Hello! to stdout: package main import "fmt" func main() { func(){ fmt.Println("Hello!") }() } play it on playground A literal function, printing the str argument to stdout: package main import "fmt&quot...