Twentyseven is a Rubik’s cube solver and one of my earliest projects in Haskell.
The first commit dates from January 2014, and version 0.0.0 was uploaded on Hackage in March 2016.
I first heard of Haskell in a course on lambda calculus in 2013. A programming language with lazy evaluation sounded like a crazy idea, so I gave it a try. Since then, I have kept writing in Haskell as my favorite language. For me it is the ideal blend of programming and math. And a Rubik’s cube solver is a great excuse for doing group theory.
Twentyseven 1.0.0 is more of a commemorative release for myself, with the goal of making it compile with the current version of GHC (9.12). There was surprisingly little breakage:
Aside from that, the code is basically just as it was 9 years ago, including design decisions that I would find questionable today. For example, I use unsafePerformIO to read precomputed tables into top-level constants, but the location of the files to read from can be configured by command-line arguments, so I better make sure that the tables are not forced before the location is set…
There’s more about the implementation of Twentyseven on my blog: Lysxia - Twentyseven 1.0.0