[Haskell-cafe] Re: haddock-2.3.0 literate comments discarded from .lhs input

On Fri, 2009-02-06 at 11:48 +0100, David Waern wrote:

2009/2/6 Alistair Bayley :

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[1 of 1] Compiling Test.Fail ( Test\Fail.hs, Test\Fail.o )

Test\Fail.hs:11:26: Can't make a derived instance of `Typeable Fail' (You need -XDeriveDataTypeable to derive an instance for this class) In the data type declaration for `Fail'

Are you processing the above module but it is called Test.Fail in reality? Have you stripped out a deriving statement from the example above? I'm very confused by this message :)

Sorry, my mistake. I pasted the error message from a different problem. This is the error I get from haddock:

C:\bayleya\eclipse\workspace\takusen\src>haddock -h --odir=doc Test/Haddock.lhs Cannot find documentation for: $named_block

Okay, then I understand.

My guess is (without looking at ghc code) that ghc just throws the literate comments away before lexing the file. This means that the Haddock comments won't be recognized.

As you say, there is also an unlitter in Cabal. I don't remember if it is invoked when using Haddock 2, but if it is, it would solve this problem.

Yes, against my better judgement the code in Cabal for haddock-2.x does not run cpp or unliting like it does for haddock-0.x. Instead it assumes that haddock-2.x will do all the cpp and unliting itself. Obviously this mean the special unliting mode that Cabal provides is not usable with haddock-2.x. The solution is to do the pre-processing the same for haddock-0.x and 2.x. Generally the haddock code in Cabal is a horrible inconsistent mess. I believe Andrea Vezzosi has been looking at rewriting it, which is good news. Duncan