Compat.Option
type 'a t = 'a option =
| None
| Some of 'a
val is_some : 'a option -> bool
is_some o is true if and only if o is Some o.
is_some o
true
o
Some o
val value : default:'a -> 'a option -> 'a
val join_list : 'a option list -> 'a list option