Hey Haskellers, I had a design question: I'm using Haskell for the first time for something other than a simple toy application. I notice I'm coming up with a lot of IO based APIs that looks something like this: type UserInfo = (String, String) -- (name, password) getMagicNumberFromHTTPServer :: UserInfo -> IO (Maybe Int) getMagicNumberFromHTTPServer user = do let curlHTTPRequest = ... --Setup curl HTTP request httpRepsponse <- ... -- Make curl HTTP request return $ tryGetMagicNumberFromResponse httpResponse I like this API, because it's easy to understand. However, I find it hard to test. In OO land, I'd create a mock CurlHTTPRequest object and pass that into the magic number logic and test for the correct usage of the curl library. Is there a FP way of achieving the same goals? I suppose given the example above I could break down the above into several smaller pure functions and test them. I don't know if this strategy will hold-up when dealing with more complex monads. Thanks for your time, Dave