``` unison
structural type M a = N | J a

d = {{

{{ docExample 0 '(x -> J x) }}

{J}

}}
```

``` ucm

  Loading changes detected in scratch.u.

  I found and typechecked these definitions in scratch.u. If you
  do an `add` or `update`, here's how your codebase would
  change:
  
    ⍟ These new definitions are ok to `add`:
    
      structural type M a
        (also named builtin.Optional)
      d : Doc2

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

  ⍟ I've added these definitions:
  
    structural type M a
      (also named builtin.Optional)
    d : Doc2

scratch/main> display d

  `x -> J x`
  
  J

```