LibYAML2.jl

A Julia wrapper for libyaml, providing fast and minimal YAML parsing.

Why LibYAML2.jl?

LibYAML.jl was unmaintained at the time LibYAML2.jl was created.

Installation

To install LibYAML2, simply use the Julia package manager:

] add LibYAML2

Usage

A basic example of parsing structured YAML data in Julia, including anchors and merge keys:

using LibYAML2

yaml_config = """
defaults: &defaults
  port: !!int 443
  enable_tls: true

server:
  <<: *defaults
  bind_address: "0.0.0.0"
  tls:
    cert_file: "/etc/certs/cert_file.pem"
    key_file: "/etc/certs/key_file.pem"

metrics:
  prometheus_enabled: true
  listen: "0.0.0.0:9100"
  service_labels: {service: "secure-backend"}

role_defaults: &role_defaults
  permissions:
    - read
    - write

users:
  - username: "admin"
    <<: *role_defaults
  - username: "stanislav"
    <<: *role_defaults
    permissions:
      - read
"""

julia> parse_yaml(yaml_config)
Dict{String, Any} with 5 entries:
  "metrics" => Dict{String,Any}("listen"=>"0.0.0.0:9100", …)
  "users"   => Any[...]
  ...

Comparison of YAML.jl and LibYAML2.jl

Feature	YAML.jl	LibYAML2.jl
Implicit type parsing	Always	Only when explicitly specified
YAML emission (serialization) support	✅	❌
!include support	❌	✅
Newline handling in quoted strings	❌ Broken	✅ Correct
Multiple top-level documents (---)	❌ (load_all_file broken)	✅
YAML 1.2 compliance	Limited	Full (via libyaml)
Pure Julia implementation	✅	❌ (uses libyaml)
Performance	Low	High

Useful Links

• libyaml – Official library repository.
• LibYAML_jll.jl – Julia wrapper for libyaml.

Contributing

Contributions to LibYAML2 are welcome! If you encounter a bug, have a feature request, or would like to contribute code, please open an issue or a pull request on GitHub.