On 06/17/2011 10:00 AM, Dmitri O.Kondratiev wrote:
Hi, I try to parse csv file with Text.CSV, like this:
import Text.CSV import System
main = do [inpFileName] <- getArgs putStrLn ("Parsing "++inpFileName++"...") let result = parseCSVFromFile inpFileName print result
=== As a result I get:
No instance for (Show (IO (Either Text.Parsec.Error.ParseError CSV))) arising from a use of `print' Possible fix: add an instance declaration for (Show (IO (Either Text.Parsec.Error.ParseError CSV)))
=== Question: How to add a Show instance for "(IO (Either Text.Parsec.Error.ParseError CSV)))" ? Hi Dmitri,
you don't add a show instance for IO, but you "unwrap" the IO Monad first and then show the result. let result = parseCSVFromFile inpFileName should be: result <- parseCSVFromFile inpFileName -- Vincent