Pretty class as alternative for Show class

[Johannes Waldmann]

Henning Thielemann wrote:

>  The Show class converts to String, the Pretty class could convert to a
> pretty printer data type like Doc. [...]

Ah yes, I use this since a long time

class ToDoc a where
    toDoc :: a -> Doc
    toDoc = toDocPrec 0 -- useful?
    toDocPrec :: Int -> a -> Doc

http://141.57.11.163/cgi-bin/cvsweb/lib/Autolib/ToDoc/


I generally make even this output re-readable,
and I'm reading is via Parsec:

class Reader a where
      readerPrec :: Int -> Parser a

http://141.57.11.163/cgi-bin/cvsweb/lib/Autolib/Reader/


and I also have the obvious DrIFT rules
that can generate standard instances for most types.

http://141.57.11.163/cgi-bin/cvsweb/drift/src/UserRuleToDoc.hs?rev=1.7
http://141.57.11.163/cgi-bin/cvsweb/drift/src/UserRuleReader.hs?rev=1.6


I will happily contribute this code to whatever Pretty class emerges.
(Well, it's free, so I'd have no way to not contribute it ...)


best regards, Johannes.