Here is a simple model for a Rubik's Cube.
My hope is to get people to see a rubik's cube as something other than "a problem to solve." It's a toy!
My two ideas are to get people to play with Haskel code _about_ the cube and (a separate idea, maybe to be explored in this model later) to make cubes with five colors, each edge and corner having the same coloring as each other. These markings will implicitly encourage people to focus on the interesting questions of how and when corners rotate and edges flip
Before I started writing this, I spent months and months carying one, and sometimes several cubes around with me. I loved watching and thinking about how the different edges and corners would travel around the cube in relationship to each other.
The basic idea of this model (below) is that you only need to keep track of the corners and edges. Each corner has three faces. Each edge has two faces. Keeping track of a face means telling where it was before any moves were made and where it is in the current state.
Choose, as a convention, the ordering, right, up, front. (Math/Physics folk: this is in anology to the "right hand rule" convention which assigns an ordering to the "x y and z" axes and determines that z will be "out of" rather than "into" the plane)
For example, the lower left front corner would be represented as (Left Left) (Down Down) (Front Front) before any moves are made Then, after a rotation about the Front face, the same corner, now in the right down front position would be represented as (Left Down) (Down Right) (Front Front).
#!/usr/bin/runhugs module Main (main) where main :: IO () main = do putStr "Not your ordinary language" data Cube = Edges Corners type Edges = [Edge] -- or Edges = Edge Edge Edge Edge Edge Edge Edge Edge Edge Edge Edge Edge type Corners = [Corner] data Edge = Face Face data Corner = Face Face Face data Face = Was Is data Was = R|L|U|D|F|B data Is = R|L|U|D|F|B