Text.PrettyPrint bug or doc bug

Benedikt Huber benjovi at gmx.net
Mon Mar 1 15:57:08 EST 2010

Ian Lynagh schrieb:
> On Wed, Feb 24, 2010 at 01:10:38PM +0100, Marcus D. Gabriel wrote:
>> The documentation for Text.PrettyPrint.HughesPJ states
>> that vcat is the "List version of $$", but it works as
>> the list version ($+$).
>> So either the documentation needs to be changed or
>> the code.  It would be nice to have both versions.
do you have a actual use case for the "List version of $$" ? It would 
make a good test I suppose.

> It looks like the behaviour changed in
> Tue Jun 24 12:37:15 BST 2008  benedikt.huber at gmail.com
>   * fillNB bug, lazy vcat
> i.e. the version that came with GHC 6.10. As it's had the current
> behaviour for some time, it would probably make sense to have a
> library submission to determine what the behaviour should be, and
> whether we want another function for the other behaviour:
>     http://www.haskell.org/haskellwiki/Library_submissions
This is indeed a bug; I've reported it back in December 2008, but 
unfortunately did not file a bug report:

(at the end of the message, starting with [1])

Personally I think the "List version of $+$" is more common, but
changing the implementation seems also fine.

It would be nice to solve the other (trickier) issue discussed in the 
mail referenced above as well.

cheers, benedikt

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