HCL - Data notation

HCL, aka HashiCorp configuration language, is an open source data notation created in 2014.

#71on PLDB

10Years Old

180kRepos

Download source code:

git clone https://github.com/hashicorp/hcl

HCL (HashiCorp Configuration Language) is a configuration language built by HashiCorp. The goal of HCL is to build a structured configuration language that is both human and machine friendly for use with command-line tools, but specifically targeted towards DevOps tools, servers, etc. HCL is also fully JSON compatible. That is, JSON can be used as completely valid input to a system expecting HCL. This helps makes systems interoperable with other systems. HCL is heavily inspired by libucl, nginx configuration, and others similar.

Tags: dataNotation
HCL is developed on GitHub and has 5,192 stars
There are at least 180,390 HCL repos on GitHub
Early development of HCL happened in HashiCorp
HCL is written in Go, HCL, Markdown, JSON, reStructuredText, Make, Bourne shell, YAML, Ruby, Python
The Google BigQuery Public Dataset GitHub snapshot shows 2k users using HCL in 3k repos on GitHub
Monaco package for syntax highlighting HCL
GitHub supports syntax highlighting for HCL
13 PLDB concepts link to HCL: Ace Editor, cloc, dgraph, edgedb, Haxe Library Manager, HCL, Hot Cocoa Lisp, ko, m3db, Mindsdb, Nomad, Semantic Patch Language, Wing

Example from the web:

variable "ami" {
   description = "the AMI to use"
}
<<FOO
hello
world
FOO

Example from Riju:

output = "Hello, world!"

Example from Linguist:

consul = "1.2.3.4"

// This is a comment
template "foo" {
  bar = "zip"
}

HCL Keywords

var local path for_each any string number bool true false null if else endif for in endfor

Language features

Feature	Supported	Example	Token
Conditionals	✓
Booleans	✓		true false
MultiLine Comments	✓	/* A comment */	/* */
Strings	✓
Comments	✓	// A comment
Line Comments	✓	// A comment	//
Semantic Indentation	X