208 lines
3.9 KiB
Markdown
208 lines
3.9 KiB
Markdown
---
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id: big-map-reference
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title: Big Maps — Scalable Maps
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---
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import Syntax from '@theme/Syntax';
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Ordinary maps are fine for contracts with a finite lifespan or a
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bounded number of users. For many contracts however, the intention is
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to have a map holding *many* entries, potentially millions of
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them. The cost of loading those entries into the environment each time
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a user executes the contract would eventually become too expensive
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were it not for *big maps*. Big maps are a data structure offered by
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Michelson which handles the scaling concerns for us. In LIGO, the
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interface for big maps is analogous to the one used for ordinary maps.
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# Declaring a Map
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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type move is int * int
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type register is big_map (address, move)
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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type move = int * int
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type register = (address, move) big_map
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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type move = (int, int);
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type register = big_map (address, move);
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```
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</Syntax>
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# Creating an Empty Big Map
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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const empty : register = big_map []
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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let empty : register = Big_map.empty
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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let empty : register = Big_map.empty
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```
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</Syntax>
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# Creating a Non-empty Map
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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const moves : register =
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big_map [
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("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) -> (1,2);
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("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address) -> (0,3)]
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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let moves : register =
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Big_map.literal [
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(("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address), (1,2));
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(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address), (0,3))]
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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let moves : register =
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Big_map.literal ([
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("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address, (1,2)),
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("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, (0,3))]);
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```
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</Syntax>
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# Accessing Values
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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const my_balance : option (move) =
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moves [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address)]
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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let my_balance : move option =
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Big_map.find_opt ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address) moves
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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let my_balance : option (move) =
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Big_map.find_opt ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address, moves);
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```
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</Syntax>
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# Updating Big Maps
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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function add (var m : register) : register is
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block {
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m [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)] := (4,9)
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} with m
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const updated_map : register = add (moves)
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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let updated_map : register =
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Big_map.update
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("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address) (Some (4,9)) moves
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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let updated_map : register =
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Big_map.update
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(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), Some ((4,9)), moves);
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```
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</Syntax>
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# Removing Bindings
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<Syntax syntax="pascaligo">
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```pascaligo group=big_maps
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function rem (var m : register) : register is
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block {
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remove ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) from map moves
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} with m
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const updated_map : register = rem (moves)
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo group=big_maps
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let updated_map : register =
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Map.remove ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) moves
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo group=big_maps
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let updated_map : register =
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Map.remove (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), moves)
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```
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</Syntax>
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