.TH "Map" 3 2024-05-31 OCamldoc "OCaml library" .SH NAME Map \- Association tables over ordered types. .SH Module Module Map .SH Documentation .sp Module .BI "Map" : .B sig end .sp Association tables over ordered types\&. .sp 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\&. .sp For instance: .EX .ft B .br \& module IntPairs = .br \& struct .br \& type t = int * int .br \& let compare (x0,y0) (x1,y1) = .br \& match Stdlib\&.compare x0 x1 with .br \& 0 \-> Stdlib\&.compare y0 y1 .br \& | c \-> c .br \& end .br \& .br \& module PairsMap = Map\&.Make(IntPairs) .br \& .br \& let m = PairsMap\&.(empty |> add (0,1) "hello" |> add (1,0) "world") .br \& .ft R .EE .sp This creates a new module .ft B PairsMap .ft R , with a new type .ft B \&'a PairsMap\&.t .ft R of maps from .ft B int * int .ft R to .ft B \&'a .ft R \&. In this example, .ft B m .ft R contains .ft B string .ft R values so its type is .ft B string PairsMap\&.t .ft R \&. .sp .sp .sp .I module type OrderedType = .B sig end .sp Input signature of the functor .ft B Map\&.Make .ft R \&. .sp .I module type S = .B sig end .sp Output signature of the functor .ft B Map\&.Make .ft R \&. .sp .I module Make : .B functor (Ord : OrderedType) -> sig end .sp Functor building an implementation of the map structure given a totally ordered type\&. .sp