[Haskell-cafe] Why MTL and Transformers?

[Gregory Crosswhite]

Something that I have been wondering for a while is:  why are there  
*still* two monad transformer libraries with seemingly identical  
functionality, especially given that they have conflicting  
namespaces?  It creates stupid problems like the one that Erik  
encountered and had to work around.

I recognize that this situation most likely came about via historical  
accident rather than by intention, but why does it continue to be true?

Cheers,
Greg