kdl - Kat's Document Language

kdl is a document language, mostly based on SDLang, with xml-like semantics that looks like you're invoking a bunch of CLI commands!

It's meant to be used both as a serialization format and a configuration language, and is relatively light on syntax compared to XML.

This repository is the place for discussing the specification.

Design and Discussion

kdl is still extremely new, and discussion about the format should happen over on the discussions page. Feel free to jump in and give us your 2 cents!

Design Principles

Maintainability
Flexibility
Cognitive simplicity and Learnability
Ease of de/serialization
Ease of implementation

These are the guiding principles behind the design of KDL, in order of importance. These principles will hopefully be useful in tie-breaking and otherwise directing specific decisions when it comes down to it. They are intentionally vague when it comes to specifics, but more concrete definitions for each one will be settled on as the project matures.

Implementations

Rust: kdl-rs

Overview

The basic syntax is similar to SDLang:

// This is a node with a single string value
title "Hello, World"

// Multiple values are supported, too
bookmarks 12 15 188 1234

// Nodes can have properties
author "Alex Monad" email="alex@example.com" active=true

// Nodes can be arbitrarily nested
contents {
  section "First section" {
    paragraph "This is the first paragraph"
    paragraph "This is the second paragraph"
  }
}

// Nodes can be separated into multiple lines
title \
  "Some title"

// Comment formats:

// C++ style

/*
C style multiline
*/

tag /*foo=true*/ bar=false

But kdl changes a few details:

// Files must be utf8 encoded!
smile "😁"

// Instead of anonymous nodes, nodes and properties can be wrapped
// in "" for arbitrary node names.
"!@#$@$%Q#$%~@!40" "1.2.3" "!!!!!"=true

// The following is a legal bare identifier:
foo123~!@#$%^&*.:'|<>/?+ "weeee"

// kdl specifically allows properties and values to be
// interspersed with each other, much like CLI commands.
foo bar=true "baz" quux=false 1 2 3

// strings can be multiline as-is, without a different syntax.
string "my
multiline
value"

// raw/unescaped strings use the "r" prefix on string literals and
// otherwise behave the same, including multiline support.
raw r"C:\Users\kdl"

// You can add any number of # after the r and the last " to
// disambiguate literal " characters.
other-raw r#"hello"world"#

// There is a single decimal number type, much like JSON's.
num 1.234e-42

// Numbers can have underscores to help readability:
bignum 1_000_000

// There is additional support for literal hexadecimal, octal, and binary input.
my-hex 0xdeadbeef
my-octal 0o755
my-binary 0b1010_1101

// You can comment out individual nodes with /-. In the case below, everything
// up until the closing `}` becomes commented.
/-mynode "foo" key=1 {
  a
  b
  c
}

// You can apply /- ("slashdash") comments to individual values, properties,
// or child blocks, too:
mynode /-"commented" "not commented" /-key="value" /-{
  a
  b
}

The following SDLang features are removed altogether:

"Anonymous" nodes
Binary data literals
Date/time formats
on and off booleans
Backtick strings
Semicolons
Namespaces with :
Shell style (#) and Lua-style (--) comments
Distinction between 32/64/128-bit numbers. There's just numbers.

License

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

lilyball / kdl