deriving_interfaces.js

// Let `Int` instancing `Eq`, `Ord` and `Show` classes, then:

var n = function (x) { return Int.make(x) }; // alias

// testing Int type
console.log(        n(4).equalTo(n(5))      );      // false
console.log(        n(3).equalTo(n(3))      );      // true
console.log(        n(4).compareTo(n(5))    );      // -1
console.log(        n(5).compareTo(n(3))    );      // 2
console.log(        n(2).compareTo(n(2))    );      // 0
console.log(        n(1234).show()          );      // "1234"


// Int tuple with all auto-derived!!!!
var TupleInt = Instance("TupleIntEq"  , Eq,
               Instance("TupleIntOrd" , Ord,
               Instance("TupleIntShow", Show,       Type("TupleInt_", [Int, Int]), {}), {}), {});

// aliases
var tup = function (a, b) { return TupleInt.make(a, b) };
var itup = function (a, b) { return TupleInt.make([Int.make(a), Int.make(b)]) };

var ta = itup(3, 5);
var tb = itup(2, 7);

console.log(        ta.equalTo(tb)        );        // false
console.log(        tb.equalTo(tb)        );        // true
console.log(        ta.compareTo(tb)      );        // 1
console.log(        tb.compareTo(ta)      );        // -1
console.log(        ta.compareTo(ta)      );        // 0
console.log(        ta.show()             );        // "3; 5"
console.log(        tb.show()             );        // "2; 7"