[hoc-users] Fwd: what to use for NULL?

[Thorsten S. <tho...@we...>]

I just discovered my error: in my code I did

panel <- _NSOpenPanel # openPanel >>= setCanChooseDirectory True

which of course let's panel end up being a () instead of an  
NSOpenPanel ()...

After fixing this, everything was fine.

In my mail to the list I deleted the important part with the intention  
not to clutter the example unneccessary... :-(

Sorry for the noise
Thorsten

Anfang der weitergeleiteten E-Mail:

> Von: Thorsten Seitz <tho...@we...>
> Datum: 30. Mai 2009 13:24:00 MESZ
> An: hoc...@li...
> Betreff: what to use for NULL?
>
> Hi,
>
> I'm just beginning to use HOC and so far I'm very happy (I did have  
> to make some adjustments to account for GHC 6.10 and a custom  
> installation location of Xcode 3).
>
> Currently I'm stuck on calling - 
> beginSheetForDirectory:file:types:modalForWindow:modalDelegate:didEndSelector:contextInfo 
> : because I don't know what to pass for (coid *)contextInfo. I  
> assumed that nullPtr would be correct, but I get a type error which  
> I do not understand.
>
> My code:
>
> panel <- _NSOpenPanel # openPanel
> panel #  
> beginSheetForDirectoryFileTypesModalForWindowModalDelegateDidEndSelectorContextInfo
> 	nil
> 	nil
> 	nil
> 	window
> 	modalDelegate
> 	(getSelectorForName selector)
> 	nullPtr
>
> The type error:
>
>     Couldn't match expected type `GHC.Ptr.Ptr
>                                     HOC-1.0:HOC.Base.ObjCObject'
>            against inferred type  
> `HOC-1.0:HOC.Arguments.EvilDummyForUnit'
>     When using functional dependencies to combine
>       ObjCArgument () HOC-1.0:HOC.Arguments.EvilDummyForUnit,
>         arising from the dependency `a -> b'
>         in the instance declaration at <no location info>
>       ObjCArgument () (GHC.Ptr.Ptr HOC-1.0:HOC.Base.ObjCObject),
>         arising from a use of  
> ` 
> beginSheetForDirectoryFileTypesModalForWindowModalDelegateDidEndSelectorContextInfo 
> '
>
> Any help will be greatly appreciated!
>
> Best regards
> Thorsten
>