[Haskell-beginners] Is this an appropriate use of the writer monad?

I need to (for class) write a minimax implementation. I'm currently doing this by functionally defining the entire tree and later pruning it down to the size I want. My assignment requires that I output the number of nodes I evaluated. I am considering wrapping the tree generation with the Writer monad (I'm not yet certain how I'd do this). Does this sound reasonable to you haskellers who know more than I? Would anyone suggest a better way? -- Alex R