marelle

Actually, ansible is a prolog. I played around with marelle[1] a bit for managing my Mac configuration and I realized that the core of the typical configuration management tool just is a prolog: it gathers facts from the systems you have, compares them with a desired state you’ve specified declaratively and executes a plan to get from the current state to the specified one. Prolog does the planning more or less “for free” because of its evaluation model. [1]: https://github.com/larsyencken/marelle

Here's a full example I wrote in Prolog for doing small scale sysadmin: https://github.com/larsyencken/marelle It mixes logic programming as imperative programming, with more logicky features like facts and rules.

Here's an example of a config system using prolog: https://github.com/larsyencken/marelle It's a hard to tell where marelle ends and the config begins, since it's all just prolog.

The best thing about prolog is how naturally search happens: state facts and rules once, then query them in many different ways. The worst part is, as the paper describes, constantly having to curb this search so that Prolog runs efficiently for normal deterministic code. Another missing piece that this paper picks up: in the real world we want to generate options in order of likelihood. The Alchemy project for AI incorporates probability this way. My understanding is that it doesn't unfortunately doesn't scale well. http://alchemy.cs.washington.edu/ Shameless plug: I revisited Prolog in recent times and wrote Marelle, a tool for test-driven sysadmin. The language is clunky by today's standards, but I still haven't seen nicer syntax for writing non-determinism. https://github.com/larsyencken/marelle

Also like the bootstrap.sh - very nicely structured and easier to verify than many others I've seen. I'd still prefer these scripts to output missing dependencies that calling sudo -- but otherwise very nice. That is, rather than: function install_git() { echo 'Trying to install git' case $(uname -s) in #... Linux) if has_exec apt-get; then apt_update sudo apt-get install -y git #... else bail "Unknown linux variant" fi ;; *) bail "Unknown operating system $(uname -s)" ;; esac } Simply aggreagate a list of missing packages, and ouput (based on a similar case-statement for detetining host): echo Please install missing packages: echo sudo apt-

A couple of other interesting applications of Prolog I haven't seen mentioned yet: Cascalog, Prolog-inspired data processing and querying library for Clojure: https://github.com/nathanmarz/cascalog Marelle, test-driven devops in SWI-Prolog: https://github.com/larsyencken/marelle

It will be ok in most cases... until it won't. What this script does is install dependencies. And fails for anything that isn't the most popular system. I really don't see the point of writing a script like this, as opposed to the following text: Requirements: git, prolog (package swi-prolog-nox, or swi-prolog). To install checkout repository https://github.com/larsyencken/marelle and run "make install" (optionally with DESTDIR=/your/custom/destination/path). Less writing, clear instructions and provided you know how to write a standard well-behaved makefile, it will also not assume surprising things about your system. Also they could ship the bin file without a static path in their repo instead of creating it on installation for some reason. Those bootstrap files are really annoying me - also because they assume zero knowledge f