// You can try out most of these statements in REPL

// Operator Binding
list = ArrayList()
list + 1
// same as list.add(1)
list[0]
// same as list.get(0)

a = BigInteger("1")
b = BigInteger("2")

addRes = a + b
// same as a.add(b)
subRes = a - b
// same as a.subtract(b)
a << 1
// same as a.shiftLeft(1)

// Data Class
data class User(id:int, name)
/*
a constructor with 0 params,
getId(), getName(), setId(id), setName(name)
toString():String, equals(o), hashCode():int
will be automatically defined
*/
// Can be instantiated in this way
User(id=1, name='cass')

// `fun` Syntax
fun empty(o)
    return o.isEmpty

['hello', 'world'].stream.filter(empty).count

// DSL
list = ArrayList()
list add 'str'
// same as list.add('str')
list set 0, 'string'
// same as list.set(0, 'string')
list clear
// same as list.clear()

// DSL allow you to form an exp like this
sql select user.id, user.name, user.age from user
// will be considered as
sql.select(user.id, user.name, user.age).from(user)

// Pre Processing define/undef
define 'CREATE TABLE' as 'class'
define 'VARCHAR' as ': String'
define 'NUMBER' as ': int'

CREATE TABLE User(
    id NUMBER
    name VARCHAR
)
// same as the following definition
class User(id : int, name : String)

inner methods
class Test
    outerMethod(i, j)
        innerMethod(k)=i+j+k
        // defines an inner method
        // which can capture the local variables
        return innerMethod(3)
        // invoke the inner method and return

// Lambda
func1 = (x)->x+2
// the default implemented interface of Lambda is
// lt::lang::function::FunctionX
// X ranges from 0 to 26

func2 : java::util::function::Function = (x)->x+3

// Lambda can work not only on functional interfaces
// but also on functional abstract classes
abstract class Func
    abstract apply()=...
func3 : Func = (x)->x+4

// 调用函数对象
var add = (a,b) -> a+b
add(1, 2) // result is 3

// JSON Literals
map = {
    'id' : 1,
    'name' : 'cass',
    'repo' : ['Latte', 'Pure.IoC']
}
// comma at the end can be omitted.

list = ['a', 'b', 'c']

// Type Definition
// classes
class User(id,name)
    getId()=id
    getName()=name
    toString():String="User("+id+", "+name+")"
    equals(o):bool
        if o is type User
            return id==o.id and name==o.name
        return false
// interfaces
interface AnInterface
    apply(o)=...