TIL to use nixpkgs.writers to quickly:

  1. Package scripts into executables with proper shebangs (e.g., Python).
  2. Bundle any dependencies.
  3. Perform checks/lints (e.g., through flake8)

I am using it in my openrouter-provisioner as follows:

server = pkgs.writers.writePython3Bin "openrouter-provisioner" {
  flakeIgnore = [
    "E501" # line too long
  ];
} (builtins.readFile ./openrouter.py);

When an LLM originally suggested this snippet, I thought it was hallucinating because I couldn’t find any reference in the manual. Then, when challenged, the LLM returned the source for the writers library. LLMs are obviously not suited for all tasks, but this is an example of something they are excellent at: they will easily discover and use less-known library features by going through the source code when the documentation is lacking.

In this particular case, the writers library includes documentation comments for most of the derivations, but none of them make it in the overall manual. I was about to open an issue but then discovered that there’s already one dating back to 2020.

# The writers

In case it’s useful, this is the Markdown documentation that would be generated and below is a list of all the included writers (some are missing from the docs):

Click to expand (LLM output of included writers)

# Base

  • makeScriptWriter - Base implementation for creating script writers
  • makeBinWriter - Base implementation for compiled language writers

# Shell

  • writeBash - Bash script writer
  • writeBashBin - Bash script writer (outputs to /bin)
  • writeDash - Dash script writer
  • writeDashBin - Dash script writer (outputs to /bin)
  • writeFish - Fish shell script writer
  • writeFishBin - Fish shell script writer (outputs to /bin)
  • writeNu - Nushell script writer
  • writeNuBin - Nushell script writer (outputs to /bin)

# Interpreted languages

  • writeBabashka - Babashka (Clojure) script writer
  • writeBabashkaBin - Babashka script writer (outputs to /bin)
  • writeGuile - Guile Scheme script writer
  • writeGuileBin - Guile Scheme script writer (outputs to /bin)
  • writeRuby - Ruby script writer
  • writeRubyBin - Ruby script writer (outputs to /bin)
  • writeLua - Lua script writer
  • writeLuaBin - Lua script writer (outputs to /bin)
  • writePerl - Perl script writer
  • writePerlBin - Perl script writer (outputs to /bin)
  • writeJS - JavaScript (Node.js) script writer
  • writeJSBin - JavaScript script writer (outputs to /bin)

# Python

  • writePython3 - Python 3 script writer
  • writePython3Bin - Python 3 script writer (outputs to /bin)
  • writePyPy2 - PyPy2 script writer
  • writePyPy2Bin - PyPy2 script writer (outputs to /bin)
  • writePyPy3 - PyPy3 script writer
  • writePyPy3Bin - PyPy3 script writer (outputs to /bin)

# Compiled Languages

  • writeHaskell - Haskell compiled script writer
  • writeHaskellBin - Haskell compiled script writer (outputs to /bin)
  • writeNim - Nim compiled script writer
  • writeNimBin - Nim compiled script writer (outputs to /bin)
  • writeRust - Rust compiled script writer
  • writeRustBin - Rust compiled script writer (outputs to /bin)
  • writeFSharp - F# script writer
  • writeFSharpBin - F# script writer (outputs to /bin)

# Specialized Writers

  • writeNginxConfig - Nginx configuration file writer

# Data Writers

  • makeDataWriter - Base transformer for writing data (deprecated)
  • writeText - Plain text file writer
  • writeJSON - JSON file writer
  • writeTOML - TOML file writer
  • writeYAML - YAML file writer