[sweetsocks21]

This delimiter first pattern is used a lot in Ocaml code as well:

Records: https://github.com/janestreet/base/blob/master/src/avltree.m...

If statements: https://github.com/janestreet/base/blob/master/src/string.ml...

Lists: https://github.com/janestreet/base/blob/master/src/string.ml...

Function calls: https://github.com/janestreet/base/blob/master/src/string.ml...

Type definitions: https://github.com/janestreet/base/blob/master/src/array.ml#...

It's not always used, shorter snippets tend to be all on one line.