proposal api: immut, shallow, deep without computed

[betula]

class A {
  @immut user = {};
  @shallow user = {};
  @deep user = {};

  @deep get user() { }
  @shallow get user() { }
  @immut get user() { }

  // or @re instead of @immut
  @re user = {};
  @re get user() { } 
}

More exported functions:

• reaction

Proposal:

• promiseTruthy
• promiseFalsy
• promiseNext

Better without reactions:

await new Promise((resolve) => reaction(expr, (ret) => ret && resolve())); // not sure