Re: [Haskell-cafe] Language.Haskell and strings

A quick glance at the code reveals that there's an instance of Pretty like such: instance Pretty HsLiteral where pretty (HsInt i) = integer i pretty (HsChar c) = text (show c) pretty (HsString s) = text (show s) pretty (HsFrac r) = double (fromRational r) That HsString instance is wrong for what you want, but there doesn't seem any way to simply override it. It should, however, be easy enough to add a further postprocessing layer to your already pretty- printed text, looking line by line for those lines that are a) too long and b) contain a very large quoted string. This layer could fairly easily do something reasonable to break the string up. Alternately, you could write a preprocessing layer that walked the source tree directly and chunked all HsStrings over a certain length into "aaaa" ++ "aaaa" ++ "aaaa", etc. At which point, the pretty printer could then decide how to distribute them properly across lines. Neither would be as perfect a solution as integrating with the pretty printer directly, but both would be helpful, and the latter could probably even be a one or two liner with an appropriate use of SYB. --Sterl On Sep 21, 2008, at 5:37 PM, Sukit Tretriluxana wrote:

Data.List

prettyStr :: Int -> String -> IO () prettyStr maxlen str = do putStr ("\"" ++ head brokenStr) mapM_ (\str -> putStr ("\\\n\\" ++ str)) (tail brokenStr) putStr "\"\n" where brokenStr = map (snd.unzip) $ groupBy (\_ (i,_) -> i `mod` maxlen /= 0) $ zip [0..] str

Ed

On Sat, Sep 20, 2008 at 4:14 PM, Maurí cio wrote: Hi,

I'm using Language.Haskell.* and would like to know if it's possible to pretty-print big strings like this:

"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"

into something like this:

"aaaaaaaa\ \aaaaaaaa\ \aaaaaaaa\ \aaaaaaaa\ \aaaaaaaa\ \aaaaaaaa\