Implementing Immutable Map of Union Types in Effect

// TypeScript Version
type _TypeA = {
  kind: "a";
  a: number;
};

type _TypeB = {
  kind: "b";
  b: string;
};

const ts = new Map<number, _TypeA | _TypeB>();

{
  const e = ts.get(1)!;

  switch (e.kind) {
    case "a":
      alert(e.a);
      break;
    case "b":
      alert(e.b);
      break;
  }
}