Re: [Gtk2hs-devel] Allocation data type not exported

[Norbert Z. <nz...@cs...>]

Thanks.  I just added the export to Widget and manually compiled it here.
I also changed the type definition of EventM as pointed out in an earlier
message I sent.  This bug is still present in the current version of
gtk2hs.  To elaborate: With the current definition of EventM

type EventM t a = ReaderT (Ptr t) IO a

it is impossible to use (EventM t) as an argument to a monad transformer,
e.g.

type EventMWithState t a = StateT MyState (EventM t) a.

There are two ways to make this possible.  Either EventM becomes a newtype,
along with the necessary boilerplate.  That's probably not necessary here.
The second option is to define

type EventM t = ReaderT (Ptr t) IO.

This allows (EventM t) to be combined with monad transformers.

Cheers,
Norbert


On Thu, Oct 30, 2014 at 3:32 AM, Axel Simon <Axe...@in...> wrote:

> Hi Norbert,
>
> On 29.10.2014, at 22:37, Norbert Zeh <nz...@cs...> wrote:
>
> > Hi folks,
> >
> > I just tried to connect to the sizeAllocate signal of the Widget type,
> but the type of this signal is Signal self (Allocation -> IO ()).  Thus,
> the function I provide as an argument needs to take an Allocation as an
> argument, but I cannot declare a function of this type because Allocation
> seems to be only exported by the hidden module
> Graphics.UI.Gtk.General.Structs.  Any advice on how to react to
> sizeAllocate signals?
> >
>
> Well, it’s a bug, it should be exported from Widget. However, it’s only a
> type synonym to Rectangle which is public, so using the Rectangle
> constructor should be possible.
>
> Cheers,
> Axel
>
> > Thanks,
> > Norbert
> >
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