Haskell Platform call for consensus: add transformers and revise the mtl package to depend on it

[Sebastiaan Visser]

Hi,

Additionally, it would be very useful to have the MaybeT monad transformer included into mtl-2. 

While migrating my packages from transformers/monads-fd to the new mtl, the absence of MaybeT was the only problem I came across.

Cheers,
Sebastiaan

On Nov 6, 2010, at 3:26 PM, Ross Paterson wrote:
> On Tue, Nov 02, 2010 at 02:17:03PM +0100, Johan Tibell wrote:
>> This is a call for consensus for the following proposal:
>> 
>>    http://trac.haskell.org/haskell-platform/wiki/Proposals/transformers
>> 
>> Are there any unresolved concerns?
> 
> Brent Yorgey's report raises one: the following functions, defined in
> the transformers package as replacements for data constructors for the
> base monads, should probably be re-exported by the new mtl:
> 
> Control.Monad.Cont:
>    cont :: ((a -> r) -> r) -> Cont r a
> Control.Monad.RWS.Lazy:
>    rws :: (r -> s -> (a, s, w)) -> RWS r w s a
> Control.Monad.RWS.Strict:
>    rws :: (r -> s -> (a, s, w)) -> RWS r w s a
> Control.Monad.Reader:
>    reader :: (r -> a) -> Reader r a
> Control.Monad.State.Lazy:
>    state :: (s -> (a, s)) -> State s a
> Control.Monad.State.Strict:
>    state :: (s -> (a, s)) -> State s a
> Control.Monad.Writer.Lazy:
>    writer :: (a, w) -> Writer w a
> Control.Monad.Writer.Strict:
>    writer :: (a, w) -> Writer w a