include module type of BatMap with module PMap := BatMap.PMap
module Pervasives := StdlibAssociation tables over ordered types.
This module implements applicative association tables, also known as finite maps or dictionaries, given a total ordering function over the keys. All operations over maps are purely applicative (no side-effects). The implementation uses balanced binary trees, and therefore searching and insertion take time logarithmic in the size of the map.
Note OCaml, Batteries Included, provides two implementations of maps: polymorphic maps and functorized maps. Functorized maps (see S and Make) are slightly more complex to use but offer stronger type-safety. Polymorphic maps make it easier to shoot yourself in the foot. In case of doubt, you should use functorized maps.
Functorized maps
The important part is the Make module which builds association maps from a user-provided datatype and comparison function. In the Make module (or its output signature S) are documentated all functions available on maps.
Here is a typical example of use:
module MyKeyType = struct
type t = my_type
let compare = my_compare_function
end
module MyMap = Map.Make(MyKeyType)
let some_map = MyMap.add something MyMap.empty
...
To define maps with integer/string keys:
module IntMap = Map.Make(Int)
module StringMap = Map.Make(String)
module type S = sig ... endFunctor building an implementation of the map structure given a totally ordered type.
Common instantiations
*
Polymorphic maps
The functions below present the manipulation of polymorphic maps, as were provided by the Extlib PMap module.
They are similar in functionality to the functorized Make module, but only uses the Pervasives.compare function to compare elements. If you need to compare using a custom comparison function, it is recommended to use the functorized maps provided by Make.
The empty map, using compare as key comparison function.
val is_empty : ('a, 'b) t -> boolReturns true if the map is empty.
val singleton : 'a -> 'b -> ('a, 'b) tCreates a new map with a single binding.
val cardinal : ('a, 'b) t -> intReturn the number of bindings of a map.
val add : 'a -> 'b -> ('a, 'b) t -> ('a, 'b) tadd x y m returns a map containing the same bindings as m, plus a binding of x to y. If x was already bound in m, its previous binding disappears. If x was already bound to some z that is physically equal to y, then the returned map is physically equal to m.
val update : 'a -> 'a -> 'b -> ('a, 'b) t -> ('a, 'b) tupdate k1 k2 v2 m replace the previous binding of k1 in m by k2 associated to v2. This is equivalent to add k2 v2 (remove k1) m, but more efficient in the case where k1 and k2 have the same key ordering. If k1 and k2 have the same key ordering and v2 is physically equal to the value k1 is bound to in m then the returned map will be physically equal to m
val update_stdlib : 'a -> ('b option -> 'b option) -> ('a, 'b) t -> ('a, 'b) tupdate_stdlib k f m returns a map containing the same bindings as m, except k has a new binding as determined by f: First, calculate y as f (find_opt k m). If y = Some v then k will be bound to v in the resulting map. Else k will not be bound in the resulting map.
If v is physically equal to the value of the previous binding of k in m, then the returned map will be physically equal to m.
This function does the same thing as update in the stdlib, but has a different name for backwards compatibility reasons.
val find_opt : 'a -> ('a, 'b) t -> 'b optionfind_opt x m returns Some b where b is the current binding * of x in m, or None if no such binding exists.
val find_default : 'b -> 'a -> ('a, 'b) t -> 'bfind_default d x m returns the current binding of x in m, or the default value d if no such binding exists.
val find_first : ('a -> bool) -> ('a, 'b) t -> 'a * 'bfind_first f m returns the first binding (k, v) for which f k is true or raises Not_found if there is no such binding. f must be monotonically increasing, i.e. if k1 < k2 && f k1 is true then f k2 must also be true.
val find_first_opt : ('a -> bool) -> ('a, 'b) t -> ('a * 'b) optionfind_first_opt f m returns Some (k, v) for the first binding (k, v) for which f k is true or returns None if there is no such binding. f must be monotonically increasing, i.e. if k1 < k2 && f k1 is true then f k2 must also be true.
val find_last : ('a -> bool) -> ('a, 'b) t -> 'a * 'bfind_last f m returns the last binding (k, v) for which f k is true or raises Not_found if there is no such binding. f must be monotonically decreasing, i.e. if k1 < k2 && f k2 is true then f k1 must also be true.
val find_last_opt : ('a -> bool) -> ('a, 'b) t -> ('a * 'b) optionfind_last_opt f m returns Some (k, v) for the last binding (k, v) for which f k is true or returns None if there is no such binding. f must be monotonically decreasing, i.e. if k1 < k2 && f k2 is true then f k1 must also be true.
val remove : 'a -> ('a, 'b) t -> ('a, 'b) tremove x m returns a map containing the same bindings as m, except for x which is unbound in the returned map. The returned map is physically equal to the passed one if x was already unbound.
val remove_exn : 'a -> ('a, 'b) t -> ('a, 'b) tremove_exn x m behaves like remove x m except that it raises an exception if x is unbound in m.
val mem : 'a -> ('a, 'b) t -> boolmem x m returns true if m contains a binding for x, and false otherwise.
val iter : ('a -> 'b -> unit) -> ('a, 'b) t -> unititer f m applies f to all bindings in map m. f receives the key as first argument, and the associated value as second argument. The order in which the bindings are passed to f is unspecified. Only current bindings are presented to f: bindings hidden by more recent bindings are not passed to f.
val map : ('b -> 'c) -> ('a, 'b) t -> ('a, 'c) tmap f m returns a map with same domain as m, where the associated value a of all bindings of m has been replaced by the result of the application of f to a. The order in which the associated values are passed to f is unspecified.
val mapi : ('a -> 'b -> 'c) -> ('a, 'b) t -> ('a, 'c) tSame as map, but the function receives as arguments both the key and the associated value for each binding of the map.
val fold : ('b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'cfold f m a computes (f kN dN ... (f k1 d1 (f k0 d0 a))...), where k0,k1..kN are the keys of all bindings in m, and d0,d1..dN are the associated data. The order in which the bindings are presented to f is unspecified.
val foldi : ('a -> 'b -> 'c -> 'c) -> ('a, 'b) t -> 'c -> 'cSame as fold, but the function receives as arguments both the key and the associated value for each binding of the map.
val at_rank_exn : int -> ('key, 'a) t -> 'key * 'aat_rank_exn i m returns the (key,value) pair whose key is at rank i in m, that is the i-th element in increasing order of the keys (the 0-th element being the smallest key in m with its associated value).
val filterv : ('a -> bool) -> ('key, 'a) t -> ('key, 'a) tfilterv f m returns a map where only the values a of m such that f a = true remain. The bindings are passed to f in increasing order with respect to the ordering over the type of the keys.
val filter : ('key -> 'a -> bool) -> ('key, 'a) t -> ('key, 'a) tfilter f m returns a map where only the (key, value) pairs of m such that f key value = true remain. The bindings are passed to f in increasing order with respect to the ordering over the type of the keys. If f returns true for all bindings of m the returned map is physically equal to m.
val filter_map : ('key -> 'a -> 'b option) -> ('key, 'a) t -> ('key, 'b) tfilter_map f m combines the features of filter and map. It calls calls f key0 a0, f key1 a1, f keyn an where a0..an are the elements of m and key0..keyn the respective corresponding keys. It returns the map of (keyi, bi) pairs such as f keyi ai = Some bi (when f returns None, the corresponding element of m is discarded).
val choose_opt : ('key, 'a) t -> ('key * 'a) optionReturn Some (k, v) for one binding (k, v) of the given map, if the map is not empty. Else, return None. Which binding is chosen is unspecified, but equal bindings will be chosen for equal maps.
val split : 'key -> ('key, 'a) t -> ('key, 'a) t * 'a option * ('key, 'a) tsplit x m returns a triple (l, data, r), where l is the map with all the bindings of m whose key is strictly less than x; r is the map with all the bindings of m whose key is strictly greater than x; data is None if m contains no binding for x, or Some v if m binds v to x.
val min_binding : ('key, 'a) t -> 'key * 'aReturns the binding with the smallest key. Raises Not_found if the map is empty.
val min_binding_opt : ('key, 'a) t -> ('key * 'a) optionReturn Some (key, value) for the key, value pair with the smallest key, or None if the map is empty.
val pop_min_binding : ('key, 'a) t -> ('key * 'a) * ('key, 'a) tReturns the binding with the smallest key along with the rest of the map.
val max_binding : ('key, 'a) t -> 'key * 'aReturn the (key, value) pair with the largest key. Raises Not_found if the map is empty.
val max_binding_opt : ('key, 'a) t -> ('key * 'a) optionReturn Some (key, value) for the key, value pair with the largest key, or None if the map is empty.
val pop_max_binding : ('key, 'a) t -> ('key * 'a) * ('key, 'a) tReturns the binding with the largest key along with the rest of the map.
Creates an enumeration for this map, enumerating (key, value) pairs with the keys in increasing order.
Creates an enumeration for this map, enumerating (key, value) pairs with the keys in decreasing order.
Return an enumeration of all the keys of a map.
Return an enumeration of all the values of a map.
Creates a map from an enumeration.
val for_all : ('a -> 'b -> bool) -> ('a, 'b) t -> boolTests whether all (key, value) pairs satisfy a predicate function.
val exists : ('a -> 'b -> bool) -> ('a, 'b) t -> boolTests whether some (key, value) pair satisfies a predicate function.
val partition : ('a -> 'b -> bool) -> ('a, 'b) t -> ('a, 'b) t * ('a, 'b) tpartition p m returns a pair of maps (m1, m2), where m1 contains all the bindings of s that satisfy the predicate p, and m2 is the map with all the bindings of s that do not satisfy p.
val add_carry : 'a -> 'b -> ('a, 'b) t -> ('a, 'b) t * 'b optionadd_carry k v m adds the binding (k, v) to m, returning the new map and optionally the previous value bound to k.
val modify : 'a -> ('b -> 'b) -> ('a, 'b) t -> ('a, 'b) tmodify k f m replaces the previous binding for k with f applied to that value. If k is unbound in m or Not_found is raised during the search, Not_found is raised.
val modify_def : 'b -> 'a -> ('b -> 'b) -> ('a, 'b) t -> ('a, 'b) tmodify_def v0 k f m replaces the previous binding for k with f applied to that value. If k is unbound in m or Not_found is raised during the search, f v0 is inserted (as if the value found were v0).
val modify_opt : 'a -> ('b option -> 'b option) -> ('a, 'b) t -> ('a, 'b) tmodify_opt k f m allow to modify the binding for k in m or absence thereof.
extract k m removes the current binding of k from m, returning the value k was bound to and the updated m.
val pop : ('a, 'b) t -> ('a * 'b) * ('a, 'b) tpop m returns a binding from m and m without that binding.
val union : ('a, 'b) t -> ('a, 'b) t -> ('a, 'b) tunion m1 m2 merges two maps, using the comparison function of m1. In case of conflicted bindings, m2's bindings override m1's. Equivalent to foldi add m2 m1. The resulting map uses the comparison function of m1.
val union_stdlib :
('key -> 'a -> 'a -> 'a option) ->
('key, 'a) t ->
('key, 'a) t ->
('key, 'a) tunion_stdlib f m1 m2 computes a map whose keys are a subset of the keys of m1 and of m2. When the same binding is defined in both arguments, the function f is used to combine them. This function is similar to merge, except f is only called if a key is present in both m1 and m2. If a key is present in either m1 or m2 but not in both, it (and the corresponding value) will be present in the resulting map.
This is the union method from the stdlib map, renamed for backwards compatibility.
val to_seq : ('key, 'a) t -> ('key * 'a) BatSeq.tIterate on the whole map, in ascending order of keys.
val to_rev_seq : ('key, 'a) t -> ('key * 'a) BatSeq.tIterate on the whole map, in descending order of keys.
val to_seq_from : 'key -> ('key, 'a) t -> ('key * 'a) BatSeq.tto_seq_from k m iterates on a subset of the bindings in m, namely those bindings greater or equal to k, in ascending order.
val add_seq : ('key * 'a) BatSeq.t -> ('key, 'a) t -> ('key, 'a) tadd the given bindings to the map, in order.
val of_seq : ('key * 'a) BatSeq.t -> ('key, 'a) tbuild a map from the given bindings
val diff : ('a, 'b) t -> ('a, 'b) t -> ('a, 'b) tdiff m1 m2 removes all bindings of keys found in m2 from m1, using the comparison function of m1. Equivalent to foldi (fun k _v m -> remove k m) m2 m1. The resulting map uses the comparison function of m1.
val intersect : ('b -> 'c -> 'd) -> ('a, 'b) t -> ('a, 'c) t -> ('a, 'd) tintersect merge_f m1 m2 returns a map with bindings only for keys bound in both m1 and m2, and with k bound to merge_f
v1 v2, where v1 and v2 are k's bindings in m1 and m2. The resulting map uses the comparison function of m1.
val merge :
('key -> 'a option -> 'b option -> 'c option) ->
('key, 'a) t ->
('key, 'b) t ->
('key, 'c) tmerge f m1 m2 computes a map whose keys is a subset of keys of m1 and of m2. The presence of each such binding, and the corresponding value, is determined with the function f. The resulting map uses the comparison function of m1.
val compare : ('b -> 'b -> int) -> ('a, 'b) t -> ('a, 'b) t -> intval equal : ('b -> 'b -> bool) -> ('a, 'b) t -> ('a, 'b) t -> boolConstruct a comparison or equality function for maps based on a value comparison or equality function. Uses the key comparison function to compare keys
Exceptionless versions of functions
module Infix : sig ... endInfix operators over a BatPMap
val (-->) : ('a, 'b) t -> 'a -> 'bMap find and insert from Infix
val (<--) : ('a, 'b) t -> ('a * 'b) -> ('a, 'b) tval bindings : ('key, 'a) t -> ('key * 'a) listReturn the list of all bindings of the given map. The returned list is sorted in increasing key order.
Added for compatibility with stdlib 3.12
Boilerplate code
Printing