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Static analysis and style linter for Ruby code.

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LASER: Lexically- and Semantically-Enriched Ruby

IRC: / #laser
Author: Michael Edgar
Copyright: 2011
License: AGPL v3.0 w/ Commercial Exceptions
Latest Version: 0.5.2
Release Date: None, yet.


LASER is a tool to analyze the lexical structure and semantic meaning of your Ruby programs. It will be able to discover bugs that Ruby only encounters at run-time, and it can discover properties about your code that no pre-existing tools can, such as whether a given block of code raises, which methods are private, if a method call could require a block, and so on. It provides warnings as well as errors for potentially error-prone code, such as:

if x = 5
  # well, x is 5 *now*

Naturally, all warnings can be ignored on a case-by-case basis with inline comments and turned off completely via command-line switches.

Feature List

Details are always forthcoming, but:

1. Optional Type System - taking some cues from Gilad Bracha's Strongtalk.
2. Style Fixing - There are many style no-nos in Ruby. LASER can find them and fix them like similar linting tools for other languages.
3. Common Semantic Analyses - dead-code discovery, yield-ability, raise-ability, unused variables/arguments, and so on.
4. Documentation Generation - By this, I mean inserting comments in your code documenting it. I don't want to try to replace YARD, which has already done tons of work in parsing docs and generating beautiful output as a result. But LASER can definitely, say, insert a @raise [SystemExitError] when it detects a call to Kernel#exit!
5. Pluggable Annotation Parsers - to get the most out of LASER, you may wish to annotate your code with types or arbitrary properties (such as method purity/impurity, visibility, etc). This requires an annotation syntax, which of course will lead to religious wars. So I'll be including the syntax I would like, as well as a parser for YARD-style annotations.
6. Ruby 1.9+ only - Yep, LASER will only run on Ruby 1.9, and it'll expect its target code is Ruby 1.9. Of course, since any 1.8 code will still parse just fine, the only issues that will come up is API differences (looking at you, String).
7. Reusable Semantic Information - I don't want a new AST format. I don't like the one provided by RubyParser and co. So I'm sticking with Ripper's AST format. It has quirks, but I prefer it, and it's part of the standard library. LASER works by creating an Array subclass called Sexp that wraps the results of a Ripper parse and does not modify its contents. So anyone expecting a typical Ripper AST can use the results of LASER's analysis. The Sexp subclass then has a variety of accessor methods created on it that contain the results of static analysis.

More to come here.


To install LASER, use the following command:

$ gem install laser

(Add sudo if you're installing under a POSIX system as root)


There are a couple of ways to use LASER. It has a command-line implementation, and a Rake task. They will be documented further in the future.


  • Jan.26.11: Not publicizing LASER yet, but I figure I need a first entry in the changelog.
  • Jun.15.11: Thesis published based on Laser. License officially switching to AGPLv3 with commercial exceptions.


LASER © 2011 by Michael Edgar. See {file:LICENSE} for licensing details.

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