You're assuming that Haskell's monadic approach is the ultimate approach to managing effects (which include delayed evaluation). Personally, I prefer the model

You're assuming that Haskell's monadic approach is the ultimate approach to managing effects (which include delayed evaluation). Personally, I prefer the model in Eff [1] and proven as an alternative to monad transformers (although, still a single-layer monad in Haskell) [2]. Eff's approach utilizes capabilities [3], called "effect instances", to restrict access to effects. Much nicer, in my opinion. Hence, I've been experimenting with the ideas in Clojure [4]. [1]: http://math.andrej.com/eff/ http://math.andrej.com/eff/ [2]: http://lambda-the-ultimate.org/node/4786 http://lambda-the-ultimate.org/node/4786 [3]: http://erights.org/elib/capability/ode/ode-capabilities.html http://erights.org/elib/capability/ode/ode-capabilities.html [4]: https://github.com/brandonbloom/cleff https://github.com/brandonbloom/cleff