Re.Viewtype t = | Sequence of t list | 
| Alternative of t list | 
| Repeat of t * int * int option | 
| Beg_of_line | 
| End_of_line | 
| Beg_of_word | 
| End_of_word | 
| Not_bound | 
| Beg_of_str | 
| End_of_str | 
| Last_end_of_line | 
| Start | 
| Stop | 
| Sem of [ `Longest | `Shortest | `First ] * t | 
| Sem_greedy of [ `Greedy | `Non_greedy ] * t | 
| Group of t | 
| No_group of t | 
| Nest of t | 
| Case of t | 
| No_case of t | 
| Intersection of t list | 
| Complement of t list | 
| Difference of t * t | 
| Pmark of int * t | 
A view of the top-level of a regex. This type is unstable and may change