OptEnvConf

Status

Used in production in all my products and some companies.

Goals

• Parse command-line arguments, environment variables, and configuration values all together.
• Self-documenting parsers for correct-by-construction documentation
• Best-in-class command-line autocompletion
• Best-in-class errors
• Formatter-friendly API

Comparison to similar projects

	opt-env-conf	optparse-applicative	envparse	autodocodec
Applicative parsing	✔️	✔️	✔️	✔️
Parsing arguments	✔️	✔️	✖️	✖️
Parsing long options	✔️	✔️	✖️	✖️
Parsing short options	✔️	✔️	✖️	✖️
Parsing short-hand short options	✔️	✔️	✖️	✖️
Parsing short-hand long options	✔️	✔️	✖️	✖️
Parsing long switches	✔️	✔️	✖️	✖️
Parsing short switches	✔️	✔️	✖️	✖️
Parsing environment variables	✔️	✖️	✔️	✖️
Parsing configuration values	✔️	✖️	✖️	✔️
Generated global --help page	✔️	✔️	✖️	✖️
Coloured global --help page	✔️	✖️	✖️	✖️
Generated per-command --help page	✔️	✔️	✖️	✖️
Coloured per-command --help page	✔️	✖️	✖️	✖️
Generated --version command	✔️	✖️	✖️	✖️
Generated manpage	✔️	✖️	✖️	✖️
Helpful parse errors	✔️	✔️	✔️	✔️
Coloured parse errors	✔️	✖️	✖️	✖️
Generated manpage	✔️	✖️	✖️	✖️
Typo suggestions	🚧	✖️	✖️	✖️
Bash completion	✔️	✔️	✖️	✖️
Zsh completion	✔️	✔️	✖️	✖️
Fish completion	✔️	✔️	✖️	✖️
Static settings check	✔️	✖️	✖️	✖️

Parsers and Interpreters

The essence of opt-env-conf is the concept of a Parser. Parsers are a tree of settings that can be interpreted in different ways. Currently, the following interpreters are provided:

• Parse the settings
• Lint the parser for common issues at runtime that were inconvenient to catch at the type level.
• Run a settings check (possibly with limited capabilities)
• Generate documentation, including a man page, a --help page, and documentation for each command recursively as well.
• Generate shell completions for Bash, Zsh, and Fish
• Generate a NixOS Option type

Example

The example application contains a fully worked example.

This example is part of the build in CI so you can rely on it being up-to-date.