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base

Full standard library replacement for OCaml
IN THIS PACKAGE

Accessors

type ('a, 'b) t
type 'a key
val sexp_of_key : ( 'a, _ ) t -> 'a key -> Sexp.t
val clear : ( _, _ ) t -> unit
val copy : ( 'a, 'b ) t -> ( 'a, 'b ) t
val fold : ( 'a, 'b ) t -> init:'c -> f:( key:'a key -> data:'b -> 'c -> 'c ) -> 'c

Attempting to modify (set, remove, etc.) the hashtable during iteration (fold, iter, iter_keys, iteri) will raise an exception.

val iter_keys : ( 'a, _ ) t -> f:( 'a key -> unit ) -> unit
val iter : ( _, 'b ) t -> f:( 'b -> unit ) -> unit
val iteri : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> unit ) -> unit

Iterates over both keys and values.

Example:

      let h = Hashtbl.of_alist_exn (module Int) [(1, 4); (5, 6)] in
      Hashtbl.iteri h ~f:(fun ~key ~data ->
        print_endline (Printf.sprintf "%d-%d" key data));;
      1-4
      5-6
      - : unit = ()
val existsi : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> bool
val exists : ( _, 'b ) t -> f:( 'b -> bool ) -> bool
val for_alli : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> bool
val for_all : ( _, 'b ) t -> f:( 'b -> bool ) -> bool
val counti : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> int
val count : ( _, 'b ) t -> f:( 'b -> bool ) -> int
val length : ( _, _ ) t -> int
val is_empty : ( _, _ ) t -> bool
val mem : ( 'a, _ ) t -> 'a key -> bool
val remove : ( 'a, _ ) t -> 'a key -> unit
val choose : ( 'a, 'b ) t -> ('a key * 'b) option
val choose_exn : ( 'a, 'b ) t -> 'a key * 'b
val set : ( 'a, 'b ) t -> key:'a key -> data:'b -> unit

Sets the given key to data.

val add : ( 'a, 'b ) t -> key:'a key -> data:'b -> [ `Ok | `Duplicate ]

add and add_exn leave the table unchanged if the key was already present.

val add_exn : ( 'a, 'b ) t -> key:'a key -> data:'b -> unit
val change : ( 'a, 'b ) t -> 'a key -> f:( 'b option -> 'b option ) -> unit

change t key ~f changes t's value for key to be f (find t key).

val update : ( 'a, 'b ) t -> 'a key -> f:( 'b option -> 'b ) -> unit

update t key ~f is change t key ~f:(fun o -> Some (f o)).

val map : ( 'a, 'b ) t -> f:( 'b -> 'c ) -> ( 'a, 'c ) t

map t f returns a new table with values replaced by the result of applying f to the current values.

Example:

      let h = Hashtbl.of_alist_exn (module Int) [(1, 4); (5, 6)] in
      let h' = Hashtbl.map h ~f:(fun x -> x * 2) in
      Hashtbl.to_alist h';;
      - : (int * int) list = [(5, 12); (1, 8)]
val mapi : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> 'c ) -> ( 'a, 'c ) t

Like map, but the function f takes both key and data as arguments.

val filter_map : ( 'a, 'b ) t -> f:( 'b -> 'c option ) -> ( 'a, 'c ) t

Returns a new table by filtering the given table's values by f: the keys for which f applied to the current value returns Some are kept, and those for which it returns None are discarded.

Example:

      let h = Hashtbl.of_alist_exn (module Int) [(1, 4); (5, 6)] in
      Hashtbl.filter_map h ~f:(fun x -> if x > 5 then Some x else None)
      |> Hashtbl.to_alist;;
      - : (int * int) list = [(5, 6)]
val filter_mapi : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> 'c option ) -> ( 'a, 'c ) t

Like filter_map, but the function f takes both key and data as arguments.

val filter_keys : ( 'a, 'b ) t -> f:( 'a key -> bool ) -> ( 'a, 'b ) t
val filter : ( 'a, 'b ) t -> f:( 'b -> bool ) -> ( 'a, 'b ) t
val filteri : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> ( 'a, 'b ) t
val partition_map : ( 'a, 'b ) t -> f:( 'b -> ( 'c, 'd ) Either.t ) -> ( 'a, 'c ) t * ( 'a, 'd ) t

Returns new tables with bound values partitioned by f applied to the bound values.

val partition_mapi : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> ( 'c, 'd ) Either.t ) -> ( 'a, 'c ) t * ( 'a, 'd ) t

Like partition_map, but the function f takes both key and data as arguments.

val partition_tf : ( 'a, 'b ) t -> f:( 'b -> bool ) -> ( 'a, 'b ) t * ( 'a, 'b ) t

Returns a pair of tables (t1, t2), where t1 contains all the elements of the initial table which satisfy the predicate f, and t2 contains the rest.

val partitioni_tf : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> ( 'a, 'b ) t * ( 'a, 'b ) t

Like partition_tf, but the function f takes both key and data as arguments.

val find_or_add : ( 'a, 'b ) t -> 'a key -> default:( unit -> 'b ) -> 'b

find_or_add t k ~default returns the data associated with key k if it is in the table t, and otherwise assigns k the value returned by default ().

val findi_or_add : ( 'a, 'b ) t -> 'a key -> default:( 'a key -> 'b ) -> 'b

Like find_or_add but default takes the key as an argument.

val find : ( 'a, 'b ) t -> 'a key -> 'b option

find t k returns Some (the current binding) of k in t, or None if no such binding exists.

val find_exn : ( 'a, 'b ) t -> 'a key -> 'b

find_exn t k returns the current binding of k in t, or raises Caml.Not_found or Not_found_s if no such binding exists.

val find_and_call : ( 'a, 'b ) t -> 'a key -> if_found:( 'b -> 'c ) -> if_not_found:( 'a key -> 'c ) -> 'c

find_and_call t k ~if_found ~if_not_found

is equivalent to:

match find t k with Some v -> if_found v | None -> if_not_found k

except that it doesn't allocate the option.

val find_and_call1 : ( 'a, 'b ) t -> 'a key -> a:'d -> if_found:( 'b -> 'd -> 'c ) -> if_not_found:( 'a key -> 'd -> 'c ) -> 'c

Just like find_and_call, but takes an extra argument which is passed to if_found and if_not_found, so that the client code can avoid allocating closures or using refs to pass this additional information. This function is only useful in code which tries to minimize heap allocation.

val find_and_call2 : ( 'a, 'b ) t -> 'a key -> a:'d -> b:'e -> if_found:( 'b -> 'd -> 'e -> 'c ) -> if_not_found:( 'a key -> 'd -> 'e -> 'c ) -> 'c
val findi_and_call : ( 'a, 'b ) t -> 'a key -> if_found:( key:'a key -> data:'b -> 'c ) -> if_not_found:( 'a key -> 'c ) -> 'c
val findi_and_call1 : ( 'a, 'b ) t -> 'a key -> a:'d -> if_found:( key:'a key -> data:'b -> 'd -> 'c ) -> if_not_found:( 'a key -> 'd -> 'c ) -> 'c
val findi_and_call2 : ( 'a, 'b ) t -> 'a key -> a:'d -> b:'e -> if_found:( key:'a key -> data:'b -> 'd -> 'e -> 'c ) -> if_not_found:( 'a key -> 'd -> 'e -> 'c ) -> 'c
val find_and_remove : ( 'a, 'b ) t -> 'a key -> 'b option

find_and_remove t k returns Some (the current binding) of k in t and removes it, or None is no such binding exists.

val merge : ( 'k, 'a ) t -> ( 'k, 'b ) t -> f: ( key:'k key -> [ `Left of 'a | `Right of 'b | `Both of 'a * 'b ] -> 'c option ) -> ( 'k, 'c ) t

Merges two hashtables.

The result of merge f h1 h2 has as keys the set of all k in the union of the sets of keys of h1 and h2 for which d(k) is not None, where:

d(k) =

  • f ~key:k (`Left d1) if k in h1 maps to d1, and h2 does not have data for k;
  • f ~key:k (`Right d2) if k in h2 maps to d2, and h1 does not have data for k;
  • f ~key:k (`Both (d1, d2)) otherwise, where k in h1 maps to d1 and k in h2 maps to d2.

Each key k is mapped to a single piece of data x, where d(k) = Some x.

Example:

      let h1 = Hashtbl.of_alist_exn (module Int) [(1, 5); (2, 3232)] in
      let h2 = Hashtbl.of_alist_exn (module Int) [(1, 3)] in
      Hashtbl.merge h1 h2 ~f:(fun ~key:_ -> function
        | `Left x -> Some (`Left x)
        | `Right x -> Some (`Right x)
        | `Both (x, y) -> if x=y then None else Some (`Both (x,y))
      ) |> Hashtbl.to_alist;;
      - : (int * [> `Both of int * int | `Left of int | `Right of int ]) list =
      [(2, `Left 3232); (1, `Both (5, 3))]
val merge_into : src:( 'k, 'a ) t -> dst:( 'k, 'b ) t -> f: ( key:'k key -> 'a -> 'b option -> 'b Base__Hashtbl_intf.Merge_into_action.t ) -> unit

Every key in src will be removed or set in dst according to the return value of f.

val keys : ( 'a, _ ) t -> 'a key list

Returns the list of all keys for given hashtable.

val data : ( _, 'b ) t -> 'b list

Returns the list of all data for given hashtable.

val filter_keys_inplace : ( 'a, _ ) t -> f:( 'a key -> bool ) -> unit

filter_inplace t ~f removes all the elements from t that don't satisfy f.

val filter_inplace : ( _, 'b ) t -> f:( 'b -> bool ) -> unit
val filteri_inplace : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> bool ) -> unit
val map_inplace : ( _, 'b ) t -> f:( 'b -> 'b ) -> unit

map_inplace t ~f applies f to all elements in t, transforming them in place.

val mapi_inplace : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> 'b ) -> unit
val filter_map_inplace : ( _, 'b ) t -> f:( 'b -> 'b option ) -> unit

filter_map_inplace combines the effects of map_inplace and filter_inplace.

val filter_mapi_inplace : ( 'a, 'b ) t -> f:( key:'a key -> data:'b -> 'b option ) -> unit
val equal : ( 'b -> 'b -> bool ) -> ( 'a, 'b ) t -> ( 'a, 'b ) t -> bool

equal f t1 t2 and similar f t1 t2 both return true iff t1 and t2 have the same keys and for all keys k, f (find_exn t1 k) (find_exn t2 k). equal and similar only differ in their types.

val similar : ( 'b1 -> 'b2 -> bool ) -> ( 'a, 'b1 ) t -> ( 'a, 'b2 ) t -> bool
val to_alist : ( 'a, 'b ) t -> ('a key * 'b) list

Returns the list of all (key, data) pairs for given hashtable.

val validate : name:( 'a key -> string ) -> 'b Validate.check -> ( 'a, 'b ) t Validate.check
val incr : ?by:int -> ?remove_if_zero:bool -> ( 'a, int ) t -> 'a key -> unit

remove_if_zero's default is false.

val decr : ?by:int -> ?remove_if_zero:bool -> ( 'a, int ) t -> 'a key -> unit