You missed my Birthday again!

[Ami]

Hi ya,

Can't believe you missed my Birthday again, give me a call when you get this e-mail.
You have to check out this great present Mel sent me, everyone at work is going mad 
over it!

www.deals2go.co.uk/script

Ami

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[Fwd: Re: Foreign import]

[Gustavo Villavicencio]

I have continued reading the bibliography on ffi but I
cannot find the solution. Please, can anyone help me?.
gustavo

 Original Message 
Subject: Re: Foreign import
From: Gustavo Villavicencio [EMAIL PROTECTED]
Date: Tue, March 4, 2003 8:35 pm
To: [EMAIL PROTECTED]

Thanks Manuel

The error message is as follows

--
CallIncr.o: In function `sWM_entry':
CallIncr.o:(.text+0xc5): undefined reference to `incr'
collect2: ld returned 1 exit status
--

where 'incr' is a toy function defined in 'mylib.h'.
Obviously, in the foreign declaration I have changed
'myfun' by 'incr'.
The compilation command is the typical

ghc -ffi -c CallIncr.hs

followed by

ghc -ffi CallIncr.o

which generate the previous error.
Thanks again,
gustavo




Manuel M T Chakravarty said:
 Gustavo Villavicencio [EMAIL PROTECTED] wrote,

 I'm a new ffi user and I have some problems with foreign import
 declaration. I'm don't have any problem to access C standard
 functions. However, I cannot access to my own functions in mylib.h by
 means of

 foreign import mylib.h myfun hmyfun :: ...

 May be I'm omitting some compilation step or parameter also, since
 I'm applying the same compilation process to call C standard
 functions.

 I'm working with ghc 5.04 on SuSe Linux 7.0.

 You should say what goes wrong.  Eg, paste the error
 messages of the compiler and/or linker into your email.

 Manuel



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Re: Comparing [Fun]Ptrs

[Manuel M T Chakravarty]

Volker Stolz [EMAIL PROTECTED] wrote,

 Hi, I'm looking for a way of comparing Ptrs to null *elegantly*.
 The FFI distinguishes between 'Ptr a' and 'FunPtr a', so testing
 would mean writing ((==) null[Fun]Ptr). This is rather tedious and a predicate
 'isNull' might be in order so that it's possible to write
 
when (isNull p) $ ...
 or
throwIOErrorIf isNull ...
 , especially without having to worry about comparing against the correct
 null pointer (FunPtr or Ptr). That's something where a class can help, but
 I'm not sure whether such a specialised class is desired...

An isNullPtr was proposed before and rejected; see the
corresponding thread in the archive of this list.  Mainly on
the grounds that people didn't consider ((==) null[Fun]Ptr)
to be tedious to write.

Besides, I really don't want to make any changes for version
1.0 of the spec anymore; except finish up the
finalizer/Foreign{Ptr,Proxy} story.  Further convenience
functions can go into extra libraries (there is no need to
stick them all in the base spec).

Cheers,
Manuel
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