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

On 8 July 2010 13:48, Ertugrul Soeylemez wrote:

Ivan Miljenovic wrote:

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On 8 July 2010 13:36, Ertugrul Soeylemez wrote:

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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.

My point was, was that if you need to pick a monad transformer library and you've never done any before, then some people are likely to choose mtl because it's currently the most-used library, it comes with the platform and if they need to interact with another package that uses a monad transformer library then it's more likely to be using mtl than anything else.

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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.

I for one don't know how to use monad transformers (I mean, I've read the section in RWH and could figure it out, but off the top of my head I can't recall how to do all the lifting stuff, etc.).

And I don't know what you mean by "pre-existing type aliases".

http://hackage.haskell.org/packages/archive/transformers/0.2.1.0/doc/html/Co... -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com