.TH "Map" 3o 2023-09-18 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