[Haskell-cafe] How to "instance MonadIO Identity"?
michael at snoyman.com
Tue Dec 28 06:32:35 CET 2010
The only way to create such an instance would be with unsafePerformIO,
which in this case would be a Very Bad Idea (tm).
On Tue, Dec 28, 2010 at 7:29 AM, Magicloud Magiclouds
<magicloud.magiclouds at gmail.com> wrote:
> From another thread in this list, I got code as:
>> instance MonadIO Identity where
>> liftIO = id
> Well, it does not work for me as:
> Couldn't match expected type `Identity a' with actual type `IO a'
> Expected type: IO a -> Identity a
> Actual type: IO a -> IO a
> In the expression: id
> In an equation for `liftIO': liftIO = id
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