[Haskell-cafe] Help understanding this type

[Branimir Maksimovic]

I use that all the time. It is for typechecking things passed to C 
functions.

Greets, Branimir.

On 11/6/18 5:35 PM, Guru Devanla wrote:
> Hello Haskell-Cafe,
>
> I have been recently studying the XMonad code and some related types 
> available in the X11 bindings library.
>
> I came across this type:
>
> newtype XEvent = XEvent XEventPtr
>
> type XEventPtr = Ptr 
> <http://hackage.haskell.org/package/base-4.10.1.0/docs/Foreign-Ptr.html#t:Ptr> 
> XEvent 
> <http://hackage.haskell.org/package/X11-1.9/docs/Graphics-X11-Xlib-Event.html#t:XEvent>
>
> Available here:
> http://hackage.haskell.org/package/X11-1.9/docs/Graphics-X11-Xlib-Event.html#t:XEvent
>
> It seems that this type is circular here. how does one use this type? 
> Is it possible to create a value out of this type? What is the use of 
> this type?
>
> Please could someone help me wrap my head around this?
>
> Thanks
>
>
>
>
>
>
>
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