Proposal: instance MonadIO Q

David Feuer david.feuer at
Thu Jul 23 20:08:27 UTC 2015

Personally I'd think it sensible to push down Control.Monad.Trans.Class,
Control.Monad.Trans.Reader, and Control.Monad.Trans.State.Strict into base.
I don't know if any Writer or RWST variants are quite ready for that sort
of treatment, and ListT obviously isn't.
On Jul 23, 2015 3:55 PM, "Edward Kmett" <ekmett at> wrote:

> Alternately we could lift MonadIO into base.
> This could be used eventually to lift more computations into MonadIO. Then
> nobody incurs an extra dependency and we have a first step towards more
> generic IO operations.
> -Edward
> On Thu, Jul 23, 2015 at 3:20 PM, Niklas Hambüchen <mail at> wrote:
>> I'd also like to mention that there's a camp of people who'd like to
>> have a safe/pure version of TH that cannot do any IO - for changes like
>> the proposed one we should check whether they'd make that more difficult.
>> On 23/07/15 20:09, David Feuer wrote:
>> > I'm very much in the "Damn the torpedoes; full speed ahead" camp most of
>> > the time, but not here. Transformers is a tiny step up from base. Why
>> > would you make it depend on template haskell rather than the other way
>> > around?
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