10 Most interesting features of Modern programming languages

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Most “modern” languages today still use the old C-style syntax.

Take a look at the chronologies of programming languages: Lisp (1958), Smalltalk (1972), Objective-C (1984), Haskell (1990), OCaml (1996), and so on. These are the languages of the last century.

In this paper, the author chose several recent languages: Reason, Swift, Kotlin and Dart as research objects and summarized 10 features:

1 Pipeline operator

A tiny grammar

let newScore = me.score

  |> double

  |> (it) => add(7, it)

  |> (it) => boundScore(0, 100, it);Copy the code

The JavaScript equivalent:

boundScore(0.100, add(7, double(me.score)));Copy the code

Es already has a corresponding proposal: TC39 / proposal-Pipeline-operator

2 Pattern matching

Kotlin grammar

when (x) {
    in 1.10. -> print("x is in the range")
    in validNumbers -> print("x is valid")!in 10.20. -> print("x is outside the range")
    else -> print("none of the above")}Copy the code

3 Reactive (Rx) programming build in the language

The Dart grammar

input.onKeyDown                                              
  .where((e) => e.ctrlKey && e.code == 'Enter')              
  .forEach((e) => dispatch(addTodoAction(e.target.value)));Copy the code

4 Default argument to the lambda function

Kotlin syntax (using it as the default argument)

strings
  .filter{ it.length == 5 }
  .map{ it.toUpperCase() }Copy the code

Compared with JavaScript

strings
  .filter{ it => it.length === 5 }
  .map{ it => it.toUpperCase() }Copy the code

5 deconstruction Destructuring

A tiny grammar:

let someInts = (10, 20);

let (ten, twenty) = someInts;



type person = {name: string, age: int};

let somePerson = {name: "Guy", age: 30};

let {name, age} = somePerson;Copy the code

Kotlin grammar

data class Person(val name: String, val age: Int)
val(name, age) = Person("Guy".20)Copy the code

Es6 already had array deconstruction, and ES8 added object deconstruction

6 Cascade operator

The Dart grammar

querySelector('#button') // Get an object.
  ..text = 'Confirm' // Use its members.
  ..classes.add('important')
  ..onClick.listen((e) => dispatch(confirmedAction()));Copy the code

The corresponding JavaScript notation

var button = querySelector('#button');
button.text = 'Confirm';
button.classed.add('important');
button.onClick.listen((e) = > dispatch(confirmedAction()));Copy the code

If you use jQuery, it’s basically the same as Dart, but there are fundamental differences

7. What is the expression

Kotlin grammar

val result = if (param == 1) {
    "one"
} else if (param == 2) {
    "two"
} else {
    "three"
}Copy the code

Some people like it, some people hate it, some people don’t care; I am very like, I have an answer on zhihu before: www.zhihu.com/question/55…

8 Try expressions

Kotlin grammar

val result = try {
    count()
} catch (e: ArithmeticException) {
    throw IllegalStateException(e)
}Copy the code

Can you use Automatic currying

A tiny grammar:

let add = (x, y) => x + y; /* same as (x) => (y) => x + y; * /

Let five = add (2, 3); / * * / 5

let alsoFive = add(2)(3); / * * / 5

let addFive = add(5); /* y => 5 + y; * /

let eleven = addFive(6); / * * /

let twelve = addFive(7); / * * / 12Copy the code

10 Method extensions

Swift grammar:

extension Int {
    func repetitions(task: (a) -> Void) {
        for _ in 0..<self {
            task()
        }
    }
}

3.repetitions({
    print("Hello!")})// Hello!
// Hello!
// Hello!Copy the code

JavaScript can be extended on prototypes.

I think there is also a very useful feature to add, option-chaining. I didn’t mention it because most languages already have this feature, but JavaScript is still too slow…

Reading text: Ten interesting features from various modern languages

Address: 10 of the most interesting features of modern programming languages

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