typeclass3.js

var traits = {};
var insts = {};

function trait(name, methods) {
    traits[name] = methods;
    insts[name] = {};
}

function struct(typeName, params, traitNames, bodys) {

    // 登録チェック用オブジェクト
    var adds = {};
    // トレイト名でループ
    for (var i = 0; i < traitNames.length; i++) {
        // トレイト名取得
        var traitName = traitNames[i];
        // メンバオブジェクト作成
        var members = {};

        if (!(traitName in traits)) {
            throw ("not found trait " + traitName);
        }
        // トレイト
        var trait = traits[traitName];

        // メンバ登録
        for (var traitMemberName in trait) {
            if (!(traitMemberName in bodys)) {
                throw ("not found trait member in " + typeName + " trait:" + traitName + " member:" + traitMemberName);
            }
            members[traitMemberName] = bodys[traitMemberName];

            // 登録チェック用
            adds[traitMemberName] = 1;
        }
        // インスタンス登録
        insts[traitName][typeName] = members;
    }

    // コンストラクタ
    var constructor = function() {
        var i = 0;
        for (var x in params) {
            this[x] = arguments[i];
            i++;
        }
    };

    // 型名保存
    constructor.prototype.typeName = typeName;
    for (var name in bodys) {
        if (!(name in adds)) {
            // 通常メンバ
            constructor.prototype[name] = bodys[name];
        }
    }
    return constructor;
}

trait("Eq1", {
    eq1: ["fun", ["self", "self"], "bool"]
});
trait("Eq2", {
    eq2: ["fun", ["self", "self"], "bool"],
    inc: ["fun", ["self"], "int"]
});

var N = struct("N", {
    "x": "int"
}, ["Eq1", "Eq2"], {
    "eq1": function(s, a) {
        return s.x == a.x;
    },
    "eq2": function(s, a) {
        return s.x == a.x;
    },
    "inc": function(s) {
        s.x++;
        return s.x;
    },
    "getX": function() {
        return this.x;
    }
});

var i = new N(20);
var j = new N(20);
console.log(i.x);
console.log(insts.Eq1[i.typeName].eq1(i, j));

console.log(insts.Eq2[i.typeName].eq2(i, j));
insts.Eq2[i.typeName].inc(i);
console.log(i.x);

console.log(insts.Eq2[i.typeName].eq2(i, j));
insts.Eq2[j.typeName].inc(j);
console.log(insts.Eq2[i.typeName].eq2(i, j));

console.log(i.getX());


var N2 = struct("N2", {
    "x": "int"
}, ["Eq1"], {
    "eq1": function(s, a) {
        return s.x == a.x;
    },
    "getX": function() {
        return this.x;
    }
});

console.log("koko");