I learned about the 'festival' in the 3rd day, so two of the puzzles are post-facto, I do am keeping up with the new puzzles! Enjoy!
Use stack install to compile and copy the final executable to your
~/.local/bin. The executable will try to parse it's first argument as int
representing the day to run, if it doesn't find one, it asks for the problem
number from stdin.
The xmas.txt files are the inputs! Change them to your own and the algorithms should work as-is.