This is a somewhat naïve solution to Sort Water Color Puzzle and the various equivalent phone games in Coalton. The code is heavily commented and intended to be read as a literate document, so take a look at <package.lisp>.
You can load the code like any Common Lisp package using asdf:load-system or
ql:quickload, and run tests using asdf:test-system, like:
CL-USER> (ql:quickload "water-sort")
CL-USER> (asdf:test-system "water-sort")
Because of the solution's naïveté, solving nontrivial puzzles will be relatively slow when using Coalton in debug mode. The tests include one such nontrivial puzzle. I recommend building in Coalton release mode with non-default SBCL compiler flags, like:
CL-USER> (push :coalton-release *features*)
CL-USER> (declaim (optimize (speed 3) (safety 1) (space 1) (debug 1) (compilation-speed 0)))
CL-USER> (asdf:load-system "coalton" :force :all)
CL-USER> (asdf:test-system "water-sort")