Proposed annotation system + dependency issue

[Simon Marlow]

Max Bolingbroke wrote:
> 2008/10/14 Ian Lynagh <igloo at earth.li>:
>> On Mon, Oct 13, 2008 at 06:06:03PM +0100, Max Bolingbroke wrote:
>>> (http://hackage.haskell.org/trac/ghc/wiki/Annotations).
>> When you say
>>    {-# ANN f id 1 #-}
>> this means you are attaching (id 1) to f, right?
>>
>> I think that that syntax is very confusing. I'm not sure what I'd prefer
>> though. Maybe parentheses, analogous to those in
>>    instance C (Maybe a)
> 
> That's a fair point: I also don't feel entirely happy with this aspect
> of the syntax. On a syntax-related note, Tristan proposed that we use
> this syntax instead for a slightly terser annotation:
> 
> {-@ f id 1 @-}
> 
> (The @ is meant to be evocative of the Java syntax for annotations).
> This might be a nice addition if we envisage annotations becoming very
> common. Furthermore, at the moment I don't think we can write:
> 
> --# INLINE foo
> 
> Is there any reason why not? It would be quite handy to be able to say:

--# is a legal symbol in Haskell 98, so in contrast to the {-# #-} syntax 
for pragmas, this could actually break existing programs.  That's why 
Haddock chose to use '-- |' rather than '--|'.

Not that I'd necessarily have a strong objection to doing this, just 
pointing out that it's not a straightforward choice.

 > --@ foo MyAnnotationConstructor

'-- @' would work, it's not stolen by Haddock currently.  However, note 
that this doesn't do what you want:

-- | docs for foo
-- @ f ANNOTATION
f :: ...

because the '-- @' line is part of the Haddock comment (the Haddock comment 
extends until the next non-comment line).

Cheers,
	Simon