gaplo917

//: Playground - noun: a place where people can play

struct Post {
    let isLiked: Bool
    let timestamp: Int64
    let content: String
}

extension Post: Equatable {
    static func == (lhs: Post, rhs: Post) -> Bool {

gaplo917

# gdate required to `brew install coreutils`
start=`gdate +%s%N`
for run in {1..10}
do
  dig blog.gaplotech.com NS @$1 > /dev/null
done
end=$(gdate +%s%N)
diff=$((end-start))
echo "Total Query Time = $((diff/1000000)) ms";

gaplo917

// http://54.169.33.162:8088/GobeeBike/app/
function checkMyCreditCard(phone, password) {  
  fetch('login?industryType=3&requestType=10001&phone=' + phone + '&password=' + password, {
    method: 'get'
  })
  .then(resp => resp.json())
  .then(response => {
    let token = response.data.token

    if(!token) throw 'You have entered a wrong phone/password!'

gaplo917

// Scala
// pattern matching in Option Type
val usernameOpt: Option[String] = Some("gary")

usernameOpt match {
    case Some("gary") => println("matched gary!")
    case Some("peter") => println("matched peter!")
    case Some(username) => println("found ${username}, but no username is matched")
    case None => println("No username is found")
}

gaplo917

// Kotlin NullableType is different from java.util.Optional or scala.Option
// it is NOT a Value Type

var str: String? = null

str == null // Compile OK! => true 

str = "gary"  // Compile OK! 

str == null // Compile OK! => false

gaplo917

// Java
// Optional Type Overhead
Optional<String> strOpt = null; // Compile OK

Optional<String> strOpt = Optional.empty(); // Compile OK

strOpt = null; // Compile OK

strOpt == null; // Compile OK => true

gaplo917

// Every Thing is an expression
val input = 1

val result = if(input == 1) "Equal to one" else "Not Equal to One"

val result2 = when(input) {
   1 -> "Equal to one"
   else -> "Not equal to one"
}

gaplo917

// Kotlin - currying function example

fun doCurrying(first: Int): (Int) -> ((Int, Int) -> Int) -> Int  {
  return { second -> { f -> f(first,second) } }
}

val add = { a: Int, b: Int -> a + b }
val multiply = { a: Int, b: Int -> a * b }
val minus = { a: Int, b: Int -> a - b }

gaplo917

data class User(val id: Int, val name: String, val address: String)

val user = User(id = 1, name = "GARY LO", address = "Hong Kong")

// Destructing order is import!!
val (userId, userName, userAddress) = user

println("id = $userId, name = $userName, address = $userAddress")
// id = 1, name = GARY LO, address = Hong Kong

gaplo917

val list = listOf(1,2,3,4,5)

// destructing the list
val (a,b,c) = list

println("a = $a, b = $b, c = $c") 
// a = 1, b = 2, c = 3

// already include in kotlin std-lib
val head = list.head