On Sun, Jul 25, 2010 at 3:40 AM, Michael Snoyman <michael@snoyman.com> wrote:
> Implementing that feature was amazingly simple. I'm still not 100% sold on
> the syntax, as I'm worried it's complicated Hamlet too much. But having the
> feature available probably isn't too dangerous. It also doesn't cause any
> problems with existing code as far as my tests go.
> As a bonus, the $forall/$maybe issue was very easy to solve: just surround
> it with parentheses.
> [$hamlet|
> $forall ((foo bar) baz) bin
>    $bin$
> |]

well done on being so quick.  I didn't even get a chance to try and
implement it myself.

The code looks very clean and accurate.  Should the spaces allowed
argument be propagated to the sub expression parser derefParens?

Also doesn't parsec have a between combinator?

i.e.
   derefParens as = between (char '(') (char ')') (deref as)
   derefSingle as = derefParens as <|> fmap DerefLeaf ident
   deref spaceAllowed = do
       let delim = if spaceAllowed
                       then (char '.' <|> (many1 (char ' ') >> return ' '))
                       else char '.'
       x <- derefSingle spaceAllowed
       xs <- many $ delim >> derefSingle
       return $ foldr1 DerefBranch $ x : xs