Decoding HMMs in Perl 6
I've wanted to write a reasonably useful Perl 6 module for a while, and I finally realised that the Viterbi algorithm would be a pretty simple place to start (hopefully it'll be useful as well).
There's a module with the same name on CPAN, but I've based the code on a Common Lisp version I wrote for school a while back. At the moment the module is pretty basic, and doesn't support assigning probabilities to unseen data for example. The module is available on GitHub.
A more advanced version will support computing the sum of the log-probabilities rather than the product, smoothing and unobserved data, and the option of mixing in a role to domain objects so that they can be passed directly to the decode method from the client code.