HSV - Hierarchical Separated Values

HSV is both a text-based file format and a streaming protocol, using ASCII control characters. Unlimited nesting (like JSON). No escaping required. Binary data supported via DLE transparency.

Spec: hsvfile.com

Features

• No escaping - Quotes, backslashes, newlines are literal data
• Streaming - STX/ETX framing with clear block boundaries
• Unlimited nesting - SO/SI for nested structures
• Binary mode - DLE transparency for raw bytes
• Parallel parsing - Records are independent, trivially parallelizable

Quick Start

use hsv::{parse, HsvValue};

// Parse a simple record
let data = "\x02name\x1fAlice\x1eage\x1f30\x03";
let doc = hsv::parse(data);

println!("{:?}", doc.records[0].get("name"));
// Some(String("Alice"))

Control Characters

Code	Hex	Symbol	Purpose
US	0x1F	␟	Key-value separator
RS	0x1E	␞	Property separator
GS	0x1D	␝	Array element separator
FS	0x1C	␜	Record separator
STX	0x02	␂	Start data block
ETX	0x03	␃	End data block
SOH	0x01	␁	Start header
SO	0x0E	␎	Start nested structure
SI	0x0F	␏	End nested structure
DLE	0x10	␐	Binary mode escape

Examples

Basic key-value

␂name␟Alice␞age␟30␃

let doc = hsv::parse("\x02name\x1fAlice\x1eage\x1f30\x03");
// records: [{"name": "Alice", "age": "30"}]

Arrays

␂tags␟admin␝user␝guest␃

let doc = hsv::parse("\x02tags\x1fadmin\x1duser\x1dguest\x03");
// records: [{"tags": ["admin", "user", "guest"]}]

Nested structures

␂user␟␎name␟Alice␞email␟a@b.com␏␃

let doc = hsv::parse("\x02user\x1f\x0ename\x1fAlice\x1eemail\x1fa@b.com\x0f\x03");
// records: [{"user": {"name": "Alice", "email": "a@b.com"}}]

Headers

␁hsv␟1.0␞type␟users␂name␟Alice␃

let doc = hsv::parse("\x01hsv\x1f1.0\x1etype\x1fusers\x02name\x1fAlice\x03");
// header: {"hsv": "1.0", "type": "users"}
// records: [{"name": "Alice"}]

Parallel vs Sequential

The default parse() function uses Rayon for parallel processing of blocks:

// Parallel (default) - faster for large inputs
let doc = hsv::parse(large_data);

// Sequential - deterministic ordering, better for small inputs
let doc = hsv::parse_sequential(small_data);

Parallel HTML Parsing

HSV enables parallel parsing of HTML-like structured documents—something research has struggled with for 30 years. See go-html-parallel/ for a proof-of-concept.

Prior research (HPar 2013, ZOOMM 2013, Servo 2017) achieved limited results due to HTML's stateful parsing model. HSV changes the question: instead of "how do we parallelize HTML parsing?" it asks "why use a format that requires sequential parsing?"

cd go-html-parallel && go test -v

Language Implementations

Language	Directory	Tests
Rust	rust/	15 passing
C++	cpp/	31 passing
C	c/	10 passing
Go	go/	12 passing
Java	java/	10 passing
Python	python/	14 passing
JavaScript/TypeScript	js/	12 passing
PHP	php/	13 passing
Perl	perl/	11 passing
Common Lisp	lisp/	28 passing
Fortran	fortran/	16 passing
COBOL	cobol/	6 passing

Python Example

import hsv

doc = hsv.parse("\x02name\x1fAlice\x1eage\x1f30\x03")
print(doc['records'])
# [{'name': 'Alice', 'age': '30'}]

Go Example

import "hsv"

doc := hsv.Parse("\x02name\x1fAlice\x1eage\x1f30\x03")
fmt.Println(doc.Records[0]["name"])
// Alice

JavaScript Example

const hsv = require('./hsv');

const doc = hsv.parse("\x02name\x1fAlice\x1eage\x1f30\x03");
console.log(doc.records[0].name);
// Alice

License

CC0 1.0 - Public Domain

HSV was formalized as an open standard by Danslav Slavenskoj, Lingenic LLC, on 2026-01-27, based on traditional ASCII control character semantics (ANSI X3.4-1963).