问题
Is there a way of converting a hash table into a list of (key,pair) values in OCaml?
I'm aware that, given a hash table ht we can do
BatList.of_enum (BatHashtbl.enum ht)
using the batteries library. This would convert the table to an enumeration and then convert the enum to a list. But I'm looking for a solution that doesn't use the Batteries Library. In the standard OCaml Hashtbl Module there doesn't seem to be a way of extracting the pairs as a list or a way of combining its functions to achieve this purpose. Any suggestions?
回答1:
In the standard OCaml Hashtbl Module there doesn't seem to be ...
Of couse there is!
val fold : ('a -> 'b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'c
So, use:
fun h -> Hashtbl.fold (fun k v acc -> (k, v) :: acc) h []
来源：https://stackoverflow.com/questions/4059978/converting-hash-table-to-list-of-pairs-key-value-in-ocaml