[Haskell-beginners] exception, not in IO

Kees Bleijenberg k.bleijenberg at lijbrandt.nl
Sun Jul 14 11:47:07 CEST 2013

The app I'am working on, converts a jsonString to another string encoding. 

The function I want to write is  jsonString -> (encoding, errorMsg)  so
String-> (String, String) 

For this purpose I have a typeable datastructure Glass. Because it is
typeable I can do (decodeJSON jsonString) :: Glass

But sometimes the jsonString is not valid (misformed or wrong fields).
decodeJSON then throws a exception.  I want to

catch that exection and transform the result to something like ("" ,
theErrorMsg). Unfortunately all catch functions want IO parameters. 

What can I do?




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/beginners/attachments/20130714/c8df2f80/attachment.htm>

More information about the Beginners mailing list