[Haskell] Haddock not being able to read interface file

[Simon Marlow]

Wolfgang Jeltsch wrote:
> Hello,
> 
> I want to generate Haddock documentation for some Haskell files and want to 
> create hyperlinks to the base package’s documentation.  I’ve downloaded 
> <http://www.haskell.org/ghc/docs/latest/html/libraries/base/base.haddock> and 
> use the option
> 
>     --read-interface=http://www.haskell.org/ghc/docs/latest/html/libraries/base,base.haddock
> 
> in my Haddock command line.  However, Haddock outputs the following:
> 
>     haddock: Warning: The interface file "base.haddock" could not be read.
>     Maybe it's from a later version of Haddock?
> 
> This happens with Haddock 0.8 as well as the current development version of 
> Haddock.

It's possible the interface files are not portable between 32 and 64-bit 
machines, and you're using one generated for a different word size.  I haven't 
verified this, but I'll make a note to check for the next version of Haddock.  I 
imagine we'll move to using Data.Binary anyway, which should fix any 
non-portability issues.

Cheers,
	Simon