unison/unison-src/transcripts/fix4424.md

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

Some basics:

```unison:hide
unique type Cat.Dog = Mouse Nat
unique type Rat.Dog = Bird

countCat = cases
  Cat.Dog.Mouse x -> Bird
```

```ucm
scratch/main> add
```

Now I want to add a constructor.

```unison:hide
unique type Rat.Dog = Bird | Mouse
```

```ucm
scratch/main> update
```