test.phs

showInt: Int => String
  = (x: Int) => `$x.toString()`: String;

showChar: Char => String
  = (x: Char) => `$x.toString()`: String;

showBool: Bool => String
  = [
    (true) => "true";
    (false) => "false";
  ];

random: {Float} = `() => Math.random()`: {Float};

showFloat: Float => String
  = (x: Float) => `$x.toString()`: String;

log: String => {Unit}
  = (x: String) => `() => console.log($x)`: {Unit};

add: Int => Int => Int
  = (x: Int) => (y: Int) => `($x + $y)`: Int;

/* ---------------------------------- */

data Nat: * [
  Zero: Nat;
  Succ: Nat => Nat;
];

natToInt: Nat => Int
  = [
    (Zero) => 0;
    (Succ(n: Nat)) => add(1, natToInt(n));
  ];

addN: Nat => Nat => Nat
  = [
    (Zero) => (y: Nat) => y;
    (Succ(x: Nat)) => (y: Nat) => Succ(addN(x, y));
  ];

three: Nat = Succ(Succ(Succ(Zero)));

four: Nat = Succ(three);

main: {Unit} = do{
  x: Float =< random;
  log(showFloat(x));

  maybeSeven: Nat = addN(three, four);
  log(showInt(natToInt(maybeSeven)));
};