Monad transformers libraries - which one to use? [closed]

Question

There are many different monad transformers libraries on Hackage. A few seem to get more attention than the others. To name a few: mtl (current version depending on transformers for some reason), transformers, monadLib, monads-tf, mtlx, contstuff.

Which one should be preferred and why? What are their unique features? What about performance?

Answer 1

The Haskell Platform specifies mtl and transformers as standard.

If you're unsure, you should just use mtl.

However, if you have a specific technical reason to look at the new libraries, they tend to address issues or add new features to mtl. monadLib in particular has some new features.