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

This transcript demonstrates that Unison forces actions in blocks to have a return type of `()`.

This works, as expected:

```unison
structural ability Stream a where emit : a -> ()

ex1 = do
  Stream.emit 1 
  Stream.emit 2
  42
```

```ucm:hide
scratch/main> add
```

This does not typecheck, we've accidentally underapplied `Stream.emit`:

```unison:error
ex2 = do
  Stream.emit
  42
```

We can explicitly ignore an unused result like so:

```unison
ex3 = do
  _ = Stream.emit
  ()
```

Using a helper function like `void` also works fine:

```unison
void x = ()

ex4 =
  void [1,2,3]
  ()
```

One more example:

```unison:error
ex4 =
  [1,2,3] -- no good
  ()
```