Haskell Platform Proposal: add transformers and revise the mtl package to depend on it

Don Stewart dons at galois.com
Tue Nov 2 14:14:37 EDT 2010

> On Tue, 2 Nov 2010, Ross Paterson wrote:
> > That requires a small change to line 58 of Network/CGI/Monad.hs:
> > 
> >   instance Monad m => Functor (CGIT m) where
> > 
> > Changing Monad to Functor will get it working with mtl >= 2, or change
> > Monad m to (Functor m, Monad m) to work with old and new versions of mtl.
> I uploaded cgi-3001.1.8.2 using (Functor m, Monad m).

Note that you've added MonadCatchIO as a dependency to cgi, which is
*not* part of the platform. This will prevent cgi being upgraded in the
next HP release.

There are three options:

    * propose MonadCatchIO be added to the platform, and get it accepted.
    * remove that dependency
    * merge MonadCatchIO functionality into some other package

-- Don

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