zarinfam

var p = new Person("Saeed", "[email protected]");
var json = toJson(p, personWriter()).as(JsObject.class);
System.out.println(json.get().get("name").as(JsString.class).get());

zarinfam

static <A> Json toJson(A value, JsonWriter<A> w){
    return w.write(value);
}

zarinfam

static JsonWriter<Person> personWriter() {
    return v -> new JsObject(Map.of("name", new JsString(v.getName()), "email", new JsString(v.getEmail())));
}

zarinfam

class Person {
    private String name;
    private String email;

    public Person(String name, String email) {
        this.name = name;
        this.email = email;
    }

    public String getName() {

zarinfam

interface JsonWriter<A> {
    Json write(A value);

    static JsonWriter<String> stringWriter() {
        return JsString::new;
    }
}

zarinfam

interface Json{
    default <T> T as(){
        return (T) this;
    }
    default <T> T as(Class<T> clazz){
        return clazz.cast(this);
    }
}

class JsObject implements Json{

zarinfam

var pairs = List.of(new Pair<>(1, "hello"), new Pair<>(2, " "), new Pair<>(3, "world"));
System.out.println(show(combineAll(pairs, deriveMonoidPair(intAdditionMonoid(), stringConcatMonoid())), showPair(showInt(), showString())));

zarinfam

interface Monoid<A> extends Empty<A> {
    A combine(A x, A y);

...

    static <A, B> Monoid<Pair<A, B>> deriveMonoidPair(Monoid<A> A, Monoid<B> B) {
        return new Monoid<>() {
            @Override
            public Pair<A, B> combine(Pair<A, B> x, Pair<A, B> y) {
                return new Pair<>(A.combine(x.getFirst(), y.getFirst()), B.combine(x.getSecond(), y.getSecond()));

zarinfam

class Pair<A, B> {
    private A first;
    private B second;

    public Pair(A first, B second) {
        this.first = first;
        this.second = second;
    }

    public A getFirst() {

zarinfam

var mPairs = List.of(
        new MPair<>(1, "hello", intAdditionMonoid(), stringConcatMonoid())
        , new MPair<>(2, " ", intAdditionMonoid(), stringConcatMonoid())
        , new MPair<>(3, "world", intAdditionMonoid(), stringConcatMonoid()));
combineAll(mPairs)
        .ifPresent(v -> System.out.println(show(v, showMPair(showInt(), showString()))));