```ucm:hide
myproject/main> builtins.merge
```

```unison
unique type Foo = Foo1
unique type Bar = X Foo
unique type Baz = X Foo

useBar : Bar -> Nat
useBar = cases
  Bar.X _ -> 1
```

```ucm
myproject/main> add
```

```unison
unique type Foo = Foo1 | Foo2
```

```ucm
myproject/main> update
```