On Wed, Dec 8, 2010 at 6:46 PM, Henk-Jan van Tuyl wrote:

On Wed, 08 Dec 2010 10:03:40 +0100, Magicloud Magiclouds wrote:

...

Hi,  Formerly, I had IORef and some state monad to do the task of keeping states.  Now in haskell 2010, I cannot find anything about it. Do I have to use ghc base package for this function?

These are not standard Haskell '98 or Haskell 2010. You can find IORef in the base package; the state monad is in both the mtl and the transformers package (mtl is deprecated). The state monad uses the multi-parameter type class extension and is therefore not in standard Haskell '98 or Haskell 2010 code. IORef also uses non-standard code.

Regards, Henk-Jan van Tuyl

-- http://Van.Tuyl.eu/ http://members.chello.nl/hjgtuyl/tourdemonad.html --

First to notice that. So standard-wise, there is no way to do state thing? -- 竹密岂妨流水过 山高哪阻野云飞

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 12/9/10 20:40 , Magicloud Magiclouds wrote:

First to notice that. So standard-wise, there is no way to do state thing?

There seems to be a lot of confusion as to what the language standard covers. It is a bare minimum; practical libraries are not part of its purview, but only the minimum needed to make implementing practical libraries possible. This includes some baked-in assumptions: for example, the "do" construct requires that the Monad typeclass support a "fail" method, numeric literals require the Num typeclass to support a "fromIntegral" method, etc., and since you can't extend typeclasses after definition that means Num and Monad are overspecified compared to other types in the language standard. Take a look at the Haskell Platform for a practical compiler-and-libraries standard. - -- brandon s. allbery [linux,solaris,freebsd,perl] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.10 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk0EI/IACgkQIn7hlCsL25Xc1wCgi9saZgo9h4RScI+ZAyR843sG eHoAn2J7Yfn664oaL1zAEZxQDLCat04k =SDlV -----END PGP SIGNATURE-----