MoreLabels.Map.Make(3)

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version 5.5.0 · 19 versions
, in arch rolling

🌸 MoreLabels.Map.Make 🌸

okay bestie, you're looking at the manual page for MoreLabels.Map.Make from the OCaml library — and yes, it's giving iconic functor energy 💅

💖 NAME 💖

MoreLabels.Map.Make — Functor building an implementation of the map structure given a totally ordered type.

🦋 Module 🦋

Module MoreLabels.Map.Make

✨ Documentation ✨

Module Make
 : (Ord : OrderedType) -> sig end

Functor building an implementation of the map structure given a totally ordered type. Literally the blueprint for making a map module, no cap 🫶

Parameters:

  • "Ord" — MoreLabels.Map.OrderedType

🗺️ Maps 🗺️

  • type key — the type of the map keys 🔑
  • type !+'a t — the type of maps from type key to type 'a 🌈
  • val empty : 'a t — the empty map. A whole lot of nothing, but make it type-safe ✨
  • val add : key:key -> data:'a -> 'a t -> 'a t — add ~key ~data m returns a map containing the same bindings as m, plus a binding of key to data. If key was already bound in m to a value that is physically equal to data, m is returned unchanged (the result of the function is then physically equal to m). Otherwise, the previous binding of key in m disappears. Old binding? Gone. Periodt 💅
Before 4.03, physical equality was not ensured.
  • val add_to_list : key:key -> data:'a -> 'a list t -> 'a list t — add_to_list ~key ~data m is m with key mapped to l such that l is data :: Map.find key m if key was bound in m and [data] otherwise. 🍓

Since 5.1

  • val update : key:key -> f:('a option -> 'a option) -> 'a t -> 'a t — update ~key ~f m returns a map containing the same bindings as m, except for the binding of key. Depending on the value of y where y is f (find_opt key m), the binding of key is added, removed or updated. If y is None, the binding is removed if it exists; otherwise, if y is Some z then key is associated to z in the resulting map. If key was already bound in m to a value that is physically equal to z, m is returned unchanged (the result of the function is then physically equal to m). 🦋

Since 4.06

  • val singleton : key -> 'a -> 'a t — singleton x y returns the one-element map that contains a binding y for x. Tiny map, main character energy 👑

Since 3.12

  • val remove : key -> 'a t -> 'a t — remove x m returns a map containing the same bindings as m, except for x which is unbound in the returned map. If x was not in m, m is returned unchanged (the result of the function is then physically equal to m). ✨
Before 4.03, physical equality was not ensured.
  • val merge : f:(key -> 'a option -> 'b option -> 'c option) -> 'a t -> 'b t -> 'c t — merge ~f m1 m2 computes a map whose keys are a subset of the keys of m1 and of m2. The presence of each such binding, and the corresponding value, is determined with the function f. In terms of the find_opt operation, we have find_opt x (merge f m1 m2) = f x (find_opt x m1) (find_opt x m2) for any key x, provided that f x None None = None. 🔥

Since 3.12

  • val union : f:(key -> 'a -> 'a -> 'a option) -> 'a t -> 'a t -> 'a t — union ~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 is a special case of merge: union f m1 m2 is equivalent to merge f' m1 m2, where:
    • f' _key None None = None
    • f' _key (Some v) None = Some v
    • f' _key None (Some v) = Some v
    • f' key (Some v1) (Some v2) = f key v1 v2

Since 4.03

  • val cardinal : 'a t -> int — return the number of bindings of a map. Counting era 💯

Since 3.12

🎀 Bindings 🎀

  • val bindings : 'a t -> (key * 'a) list — return the list of all bindings of the given map. The returned list is sorted in increasing order of keys with respect to the ordering Ord.compare, where Ord is the argument given to MoreLabels.Map.Make. Sorted and slaying ✨

Since 3.12

  • val min_binding : 'a t -> key * 'a — return the binding with the smallest key in a given map (with respect to the Ord.compare ordering), or raise Not_found if the map is empty. 🥺

Since 3.12

  • val min_binding_opt : 'a t -> (key * 'a) option — return the binding with the smallest key in the given map (with respect to the Ord.compare ordering), or None if the map is empty. Option vibes 🌸

Since 4.05

  • val max_binding : 'a t -> key * 'a — same as MoreLabels.Map.S.min_binding, but returns the binding with the largest key in the given map. Big key energy 👑

Since 3.12

  • val max_binding_opt : 'a t -> (key * 'a) option — same as MoreLabels.Map.S.min_binding_opt, but returns the binding with the largest key in the given map.

Since 4.05

  • val choose : 'a t -> key * 'a — return one binding of the given map, or raise Not_found if the map is empty. Which binding is chosen is unspecified, but equal bindings will be chosen for equal maps. Mystery pick, but consistent 🎀

Since 3.12

  • val choose_opt : 'a t -> (key * 'a) option — return one binding of the given map, or None if the map is empty. Which binding is chosen is unspecified, but equal bindings will be chosen for equal maps. ✨

Since 4.05

🔍 Searching 🔍

  • val find : key -> 'a t -> 'a — find x m returns the current value of x in m, or raises Not_found if no binding for x exists. 🔎
  • val find_opt : key -> 'a t -> 'a option — find_opt x m returns Some v if the current value of x in m is v, or None if no binding for x exists. Soft-launch searching 🌸

Since 4.05

  • val find_first : f:(key -> bool) -> 'a t -> key * 'a — find_first ~f m, where f is a monotonically increasing function, returns the binding of m with the lowest key k such that f k, or raises Not_found if no such key exists. 💫

For example, find_first (fun k -> Ord.compare k x >= 0) m will return the first binding k, v of m where Ord.compare k x >= 0 (intuitively: k >= x), or raise Not_found if x is greater than any element of m.

Since 4.05

  • val find_first_opt : f:(key -> bool) -> 'a t -> (key * 'a) option — find_first_opt ~f m, where f is a monotonically increasing function, returns an option containing the binding of m with the lowest key k such that f k, or None if no such key exists. 🦋

Since 4.05

  • val find_last : f:(key -> bool) -> 'a t -> key * 'a — find_last ~f m, where f is a monotonically decreasing function, returns the binding of m with the highest key k such that f k, or raises Not_found if no such key exists. 🔥

Since 4.05

  • val find_last_opt : f:(key -> bool) -> 'a t -> (key * 'a) option — find_last_opt ~f m, where f is a monotonically decreasing function, returns an option containing the binding of m with the highest key k such that f k, or None if no such key exists. 💜

Since 4.05

🚶 Traversing 🚶

  • val iter : f:(key:key -> data:'a -> unit) -> 'a t -> unit — iter ~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 bindings are passed to f in increasing order with respect to the ordering over the type of the keys. Walk through it, bestie ✨
  • val fold : f:(key:key -> data:'a -> 'acc -> 'acc) -> 'a t -> init:'acc -> 'acc — fold ~f m ~init computes (f kN dN ... (f k1 d1 init)...), where k1 ... kN are the keys of all bindings in m (in increasing order), and d1 ... dN are the associated data. Fold it up, iconic behavior 🎀

🪄 Transforming 🪄

  • val map : f:('a -> 'b) -> 'a t -> 'b t — map ~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 bindings are passed to f in increasing order with respect to the ordering over the type of the keys. Glow-up for every value 💅
  • val mapi : f:(key -> 'a -> 'b) -> 'a t -> 'b t — same as MoreLabels.Map.S.map, but the function receives as arguments both the key and the associated value for each binding of the map. Key AND value? Obsessed 💖
  • val filter : f:(key -> 'a -> bool) -> 'a t -> 'a t — filter ~f m returns the map with all the bindings in m that satisfy predicate f. If every binding in m satisfies f, m is returned unchanged (the result of the function is then physically equal to m). Keep only the ones that pass the vibe check ✅
Before 4.03, physical equality was not ensured.

Since 3.12

  • val filter_map : f:(key -> 'a -> 'b option) -> 'a t -> 'b t — filter_map ~f m applies the function f to every binding of m, and builds a map from the results. For each binding (k, v) in the input map:
-if f k v is None then k is not in the result,

-if f k v is Some v' then the binding (k, v') is in the output map.

For example, the following function on maps whose values are lists

filter_map
  (fun _k li -> match li with [] -> None | _::tl -> Some tl)
  m

drops all bindings of m whose value is an empty list, and pops the first element of each value that is non-empty. 🍓

Since 4.11

  • val partition : f:(key -> 'a -> bool) -> 'a t -> 'a t * 'a t — partition ~f m returns a pair of maps (m1, m2), where m1 contains all the bindings of m that satisfy the predicate f, and m2 is the map with all the bindings of m that do not satisfy f. Split into yes and no, literally 🌈

Since 3.12

  • val split : key -> 'a t -> 'a t * 'a option * 'a t — split 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. Three-part reveal ✨

Since 3.12

✅ Predicates and comparisons ✅

  • val is_empty : 'a t -> bool — test whether a map is empty or not. Empty check, no cap 🫶
  • val is_singleton : 'a t -> bool — test whether a map has exactly one element or not. Solo map check 👑

Since 5.5

  • val mem : key -> 'a t -> bool — mem x m returns true if m contains a binding for x, and false otherwise. Is it in there or not? 🔍
  • val equal : cmp:('a -> 'a -> bool) -> 'a t -> 'a t -> bool — equal ~cmp m1 m2 tests whether the maps m1 and m2 are equal, that is, contain equal keys and associate them with equal data. cmp is the equality predicate used to compare the data associated with the keys. Twin check 💖
  • val compare : cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int — total ordering between maps. The first argument is a total ordering used to compare data associated with equal keys in the two maps. Ranking era 📈
  • val for_all : f:(key -> 'a -> bool) -> 'a t -> bool — for_all ~f m checks if all the bindings of the map satisfy the predicate f. Everyone has to pass ✅

Since 3.12

  • val exists : f:(key -> 'a -> bool) -> 'a t -> bool — exists ~f m checks if at least one binding of the map satisfies the predicate f. Just one is enough, periodt 💅

Since 3.12

🔄 Converting 🔄

  • val to_list : 'a t -> (key * 'a) list — to_list m is MoreLabels.Map.S.bindings m. Map to list, easy 🎀

Since 5.1

  • val of_list : (key * 'a) list -> 'a t — of_list bs adds the bindings of bs to the empty map, in list order (if a key is bound twice in bs the last one takes over). Last one wins, no cap 👑

Since 5.1

  • val to_seq : 'a t -> (key * 'a) Seq.t — iterate on the whole map, in ascending order of keys. Sequence time ⭐

Since 4.07

  • val to_rev_seq : 'a t -> (key * 'a) Seq.t — iterate on the whole map, in descending order of keys. Reverse sequence, still slaying 🔥

Since 4.12

  • val to_seq_from : key -> 'a t -> (key * 'a) Seq.t — to_seq_from k m iterates on a subset of the bindings of m, in ascending order of keys, from key k or above. Start from k and go up 🦋

Since 4.07

  • val add_seq : (key * 'a) Seq.t -> 'a t -> 'a t — okay so this one is literally “add the given bindings to the map, in order” 💅. You bring the sequence of key/value pairs, it does the lil’ insertion dance, and you get an 'a t back. Since 4.07
  • val of_seq : (key * 'a) Seq.t -> 'a t — bestie, this is the build-a-map-from-the-given-bindings button ✨. Hand it a (key * 'a) Seq.t, receive an 'a t, no cap. Since 4.07

and that’s the page, bestie 🫶 — the footer says OCamldoc, dated 2026-06-22, for MoreLabels.Map.Make(3). iconic.

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