CAst'a CAst.t wraps a value of type 'a with (optional) source location information. It is notably used to add location information to AST nodes.
val map_from_loc : (?loc:Loc.t -> 'a -> 'b) -> 'a Loc.located -> 'b tval with_val : ('a -> 'b) -> 'a t -> 'bmodule Smart : sig ... end