[Haskell-cafe] Re: Transformers versus monadLib versus...

Ertugrul Soeylemez es at ertes.de
Wed Jul 7 23:48:04 EDT 2010

Ivan Miljenovic <ivan.miljenovic at gmail.com> wrote:

> On 8 July 2010 13:36, Ertugrul Soeylemez <es at ertes.de> wrote:
> > To be honest, I don't know any strength of MTL compared to
> > transformers and monadLib.  Actually even transformers is quite
> > primitive compared to monadLib.  The only real advantage is that it
> > has flipped run functions and a built-in MaybeT.
> mtl's advantages: wide pre-existing user base, etc.

As said, I don't think this is a valid argument.  Windows has a much
larger user base than Linux.  C++ has a much larger user base than
Haskell.  We still use Haskell, and many of us use Linux.

> transformers (especially when used with monads-{fd,tf}) advantage over
> monadLib: pre-existing type aliases, documentation, easier to port old
> code that was using mtl.

If you don't use monadLib-specific features, then most code will run in
monadLib as well as transformers without changes.  The Haddock
documentation of monadLib is quite brief, but if you know how to use
monad transformers, you won't have any problems.  And I don't know what
you mean by "pre-existing type aliases".


nightmare = unsafePerformIO (getWrongWife >>= sex)

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