.TH "Map" 3o source: 2019-01-25 OCamldoc "OCaml library"
.SH NAME
Map \- Association tables over ordered types.
.SH Module
Module   Map
.SH Documentation
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Module
.BI "Map"
 : 
.B sig  end

.sp
Association tables over ordered types\&.
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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\&.
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For instance:
.B 
.B      module IntPairs =
.B        struct
.B          type t = int * int
.B          let compare (x0,y0) (x1,y1) =
.B            match Pervasives\&.compare x0 x1 with
.B                0 \-> Pervasives\&.compare y0 y1
.B              | c \-> c
.B        end
.B 
.B      module PairsMap = Map\&.Make(IntPairs)
.B 
.B      let m = PairsMap\&.(empty |> add (0,1) "hello" |> add (1,0) "world")
.B    
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This creates a new module 
.B PairsMap
, with a new type 
.B \&'a PairsMap\&.t
of maps from 
.B int * int
to 
.B \&'a
\&. In this example, 
.B m
contains 
.B string
values so its type is 
.B string PairsMap\&.t
\&.

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.sp
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.I module type OrderedType = 
.B sig  end

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Input signature of the functor 
.B Map\&.Make
\&.

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.I module type S = 
.B sig  end

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Output signature of the functor 
.B Map\&.Make
\&.

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.I module Make : 
.B functor (Ord : OrderedType) -> sig  end

.sp
Functor building an implementation of the map structure
given a totally ordered type\&.

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