This is the web site of Denis Defreyne, a software engineer living in Berlin.


I write software! Here’s an incomplete list of the stuff I made and am working on. All of it is freely available as open source under the MIT license.


The following pieces of software have been around for a significant amount of time, are battle-tested and considered stable. You can rely on them.

adsf is a web server that you can launch instantly in any directory.

cri helps build command-line applications in Ruby.

ddmemoize implements memoization for Ruby.

ddmetrics records and analyses runtime measurements for Ruby apps.

ddplugin is a Ruby library for handling plugins.

nanoc is a fast and flexible static-site generator.

slow_enumerator_tools supports merging, buffering, … Ruby enumerators.


The following pieces of software are work in progress. Their APIs are unstable, they are buggy, but… they are probably more exciting than the production-ready ones. Play around with them, but don’t use them for real work.

d★mark is a semantically-rich markup language for prose.

d★parse is a parser combinator library for Ruby.

d★stream allows writing stream-processing code in Ruby.

glove is a game engine for Crystal.

rcpu is a VM emulator and assembler written in Crystal.