Re: [Haskell-cafe] pretty printing with comments

It's not an easy problem to pretty print (i.e. change indentation) and preserve the comments. And always get it right. On Tue, Oct 20, 2009 at 1:28 PM, Pasqualino "Titto" Assini wrote:

Thanks Niklas,

in fact this produced a source with comments:

import Language.Haskell.Exts.Annotated

main = do  (ParseOk (mod,comments)) <- parseFileWithComments defaultParseMode "Test.hs"  let pretty = exactPrint mod comments  writeFile "Test_PRETTY.hs" pretty

However: - The source code produced was incorrect:

class Dir d where

was rewritten as:

class Dir dwhere{

And:

instance Dir Directory where  localDir (Local f) = return f

type URL= String

was rewritten as:

instance Dir Directory where  localDir (Local f) = return f

 typeURL= String

Are these known bugs?

- Also, the printing is a bit too exact :-), I would like to keep my comments AND get the code nicely reformatted.

Is there a way?

What people use to keep their haskell source files in tip-top shape?

Thanks

         titto

2009/10/20 Niklas Broberg :

...

Hi Pasqualino,

...

I am looking at the haskell-src-ext library.

It can parse files with comments and it can pretty print but, for what I can see it cannot do both :-)  (prettyPrint won't work on the structure returned by parseFileWithComments).

What you want is exactPrint, defined in Language.Haskell.Exts.Annotated.ExactPrint. :-)

Cheers,

/Niklas

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