| Change of loc * ('term, 'lazy_term, 'ident) pattern * 'lazy_term
| Clear of loc * 'ident list
| ClearBody of loc * 'ident
+ | Compose of loc * 'term * 'term * 'ident intros_spec
| Constructor of loc * int
| Contradiction of loc
| Cut of loc * 'ident option * 'term