How to parse a YAML file in Elixir using yamerl?

Start the yamerl application with Application.start(:yamerl), then use :yamerl_constr.file(filename) for simple mode or add :detailed_constr option for metadata. The README provides a complete Mix example with dependency setup.

yamerl vs fast_yaml for Erlang YAML parsing?

yamerl is pure Erlang and dependency-free, ideal for portability, while fast_yaml uses NIFs for better performance but adds native code dependencies. Choose yamerl for safety in restricted environments, fast_yaml for speed-critical applications.

Can yamerl handle YAML anchors and aliases?

The README doesn't explicitly mention support for YAML anchors and aliases; given its focus on YAML 1.2 basics, it might lack full feature parity with more comprehensive parsers, so check the detailed documentation for edge cases.

How to stream large JSON files with yamerl?

Use yamerl_constr:new/1 to create a parser state, feed chunks with next_chunk/2, and finalize with last_chunk/2. This incremental approach prevents memory bloat, as shown in the streaming API example.

Does yamerl support YAML 1.2 fully?

Yes, yamerl parses YAML 1.1 and 1.2 specifications, but it's pure Erlang, so some complex features or performance optimizations might be limited compared to native implementations. Refer to the official docs for compliance details.

yamerl or jiffy for JSON parsing in Erlang?

yamerl adds YAML support and is dependency-free, while jiffy is a NIF-based JSON parser that's faster for JSON-only tasks. Use yamerl if you need both formats or avoid native code; otherwise, jiffy for better JSON performance.

Open-Awesome

yamerl

BSD-2-ClauseErlangv0.10.0

A pure Erlang application for parsing YAML 1.2 and JSON documents with no external dependencies.

GitHub

212 stars59 forks0 contributors

What is yamerl?

yamerl is a YAML 1.2 and JSON parser written in pure Erlang. It allows developers to parse and construct data from YAML and JSON documents without any external dependencies, providing both simple and detailed output modes for flexible data handling.

Target Audience

Erlang and Elixir developers who need to parse YAML or JSON configuration files, data streams, or serialized documents within their applications.

Value Proposition

Developers choose yamerl for its dependency-free, pure Erlang implementation that ensures portability and safety, along with support for both YAML and JSON parsing in a single library.

Overview

YAML 1.2 and JSON parser in pure Erlang

Use Cases

Best For

Parsing YAML configuration files in Erlang/OTP applications
Handling JSON data within Elixir projects via Erlang interoperability
Streaming large YAML or JSON documents incrementally
Integrating YAML/JSON parsing in environments where external dependencies are restricted
Converting YAML documents to detailed Erlang records with metadata
Processing multi-document YAML streams in server-side Erlang systems

Not Ideal For

High-throughput systems requiring native-code parsing speed for massive datasets
Projects needing full YAML 1.3 compliance or advanced features like schema validation
Teams prioritizing extensive IDE integrations or graphical tooling for data inspection
Applications where JSON parsing is the sole requirement and more optimized, JSON-specific libraries are preferred

Pros & Cons

Pros

Dependency-Free Portability

Pure Erlang implementation with no NIFs or external dependencies, ensuring it runs on any Erlang/OTP platform without compatibility issues.

Dual Format Support

Parses both YAML 1.1/1.2 and JSON from strings, files, or streams, reducing library bloat in mixed-data environments.

Flexible Output Modes

Offers simple Erlang structures for quick integration and detailed records with metadata like line/column for debugging or precise error handling.

Streaming for Large Documents

Provides a chunk-based API for incremental parsing, allowing handling of large files without loading entire documents into memory.

Cons

Performance Overheads

Pure Erlang implementation may be slower than parsers using native code (NIFs) for CPU-intensive parsing tasks, impacting high-volume scenarios.

Manual Application Start Required

Users must explicitly call application:start(yamerl) before use, an extra step that can lead to runtime errors if omitted, unlike some auto-starting libraries.

Sparse Ecosystem and Tooling

As a niche library, it lacks extensive community plugins, IDE support, or third-party tools compared to more mainstream parsers in other languages.

Frequently Asked Questions

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