I've copied this from http://stackoverflow.com/questions/5010267/haskell-abstracting-a-genetic-alg... as someone suggested that it might spark an interesting discussion I'm new to the world of Haskell programming and I'm cutting my teeth on a simple genetic algorithm for finding good solutions to the Travelling Salesman problem. I am representing the solutions as permutations on Integers and so I have this type synonym type Genome = [Int] The algorithm itself is a set of functions which operate on the solutions: mutation :: Genome -> Genome selectParents :: [Genome] -> [Genome] -> [Genome] crossover :: Genome -> Genome -> (Genome, Genome) selectSurvivors :: [Genome] -> [Genome] -> [Genome] I'm not sure how much of my code is relevant to my question so please ask if more details are needed. One thing that might be worth mentioning is that the type signatures above are actually simplified, I am in fact using the State monad to carry around an StdGen so all of these functions actually return stateful computations. There are several things which I would like to do with this but can't quite get my head around. I want to make it possible to choose different representations for the solutions, it seems to me that this would be a natural place to use a type class, so that Genome would be the type class and [Int] a specific instance of this Genome. Now, I want to be able to experiment with the implementations, and I want to be able to use the code in other projects. Using a type class like this would require that every new algorithm I create would require me to create another instance of Genome, is this a good way to go about creating a library? One bonus question, just a thing that's been bothering me, is there any way to create something like a type synonym for a function so that if I'm writing a function which takes functions as arguments I can write the synonym rather than the whole type signature of the function i.e so that something like the following would work. type someFunc = [Int] -> [Int] -> Int someOtherFunc :: someFunc -> [Int] -> Int Right, hopefully that's a lucid enough explanation of the problem, feel like I've missed the really obvious answer but it hasn't jumped out at me. Cheers