193 lines
4.5 KiB
Markdown
193 lines
4.5 KiB
Markdown
---
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id: bytes-reference
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title: Bytes
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description: Operations on bytes
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hide_table_of_contents: true
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---
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import Syntax from '@theme/Syntax';
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import SyntaxTitle from '@theme/SyntaxTitle';
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<SyntaxTitle syntax="pascaligo">
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function concat : bytes -> bytes -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="cameligo">
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val concat : bytes -> bytes -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="reasonligo">
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let concat: (bytes, bytes) => bytes
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</SyntaxTitle>
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Concatenate together two `bytes` arguments and return the result.
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<Syntax syntax="pascaligo">
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```pascaligo
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function concat_op (const s : bytes) : bytes is Bytes.concat(s , 0x7070)
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```
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> Note that `bytes_concat` is *deprecated*.
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo
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let concat_op (s : bytes) : bytes =
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Bytes.concat s 0x7070
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo
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let concat_op = (s: bytes): bytes => Bytes.concat(s, 0x7070);
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```
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</Syntax>
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<SyntaxTitle syntax="pascaligo">
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function sub : nat -> nat -> bytes -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="cameligo">
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val sub : nat -> nat -> bytes -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="reasonligo">
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let sub : (nat, nat, bytes) => bytes
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</SyntaxTitle>
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Extract the bytes between `pos1` and `pos2`. **Positions are zero indexed and
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inclusive**. For example if you gave the input "ff7a7aff" to the following:
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<Syntax syntax="pascaligo">
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```pascaligo
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function slice_op (const s : bytes) : bytes is Bytes.sub(1n , 2n , s)
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```
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> Note that `bytes_slice` is *deprecated*.
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo
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let slice_op (s : bytes) : bytes = Bytes.sub 1n 2n s
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```
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> Note that `Bytes.slice` is *deprecated*.
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</Syntax>
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<Syntax syntax="reasonligo">
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```
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let slice_op = (s: bytes): bytes => Bytes.sub(1n, 2n, s);
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```
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> Note that `Bytes.slice` is *deprecated*.
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</Syntax>
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It would return "7a7a" rather than "ff7a" or "ff" or "7a".
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<SyntaxTitle syntax="pascaligo">
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function pack : 'a -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="cameligo">
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val pack : 'a -> bytes
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</SyntaxTitle>
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<SyntaxTitle syntax="reasonligo">
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let pack : 'a => bytes
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</SyntaxTitle>
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Converts Michelson data structures to a binary format for serialization.
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> ⚠️ `PACK` and `UNPACK` are features of Michelson that are intended to be used by people that really know what they're doing. There are several failure cases (such as `UNPACK`ing a lambda from an untrusted source), most of which are beyond the scope of this document. Don't use these functions without doing your homework first.
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<Syntax syntax="pascaligo">
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```pascaligo
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function id_string (const p : string) : option(string) is block {
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const packed : bytes = bytes_pack(p) ;
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} with (bytes_unpack(packed): option(string))
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo
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let id_string (p: string) : string option =
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let packed: bytes = Bytes.pack p in
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((Bytes.unpack packed): string option)
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo
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let id_string = (p: string) : option(string) => {
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let packed : bytes = Bytes.pack(p);
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((Bytes.unpack(packed)): option(string));
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};
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```
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</Syntax>
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<SyntaxTitle syntax="pascaligo">
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function unpack : bytes -> option 'a
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</SyntaxTitle>
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<SyntaxTitle syntax="cameligo">
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val unpack : bytes -> 'a option
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</SyntaxTitle>
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<SyntaxTitle syntax="reasonligo">
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let unpack: bytes => option('a)
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</SyntaxTitle>
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Reverses the result of using `pack` on data.
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As the conversion might fail an option type is returned.
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> ⚠️ `PACK` and `UNPACK` are features of Michelson that are intended to be used by people that really know what they're doing. There are several failure cases (such as `UNPACK`ing a lambda from an untrusted source), most of which are beyond the scope of this document. Don't use these functions without doing your homework first.
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<Syntax syntax="pascaligo">
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```pascaligo
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function id_string (const p : string) : option(string) is block {
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const packed : bytes = bytes_pack(p) ;
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} with (bytes_unpack(packed): option(string))
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```
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</Syntax>
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<Syntax syntax="cameligo">
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```cameligo
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let id_string (p: string) : string option =
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let packed: bytes = Bytes.pack p in
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((Bytes.unpack packed): string option)
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```
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</Syntax>
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<Syntax syntax="reasonligo">
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```reasonligo
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let id_string = (p: string) : option(string) => {
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let packed : bytes = Bytes.pack(p);
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((Bytes.unpack(packed)): option(string));
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};
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```
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</Syntax>
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<SyntaxTitle syntax="pascaligo">
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function length : bytes -> nat
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</SyntaxTitle>
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<SyntaxTitle syntax="cameligo">
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val length : bytes -> nat
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</SyntaxTitle>
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<SyntaxTitle syntax="reasonligo">
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let length: bytes => nat
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</SyntaxTitle>
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