Unwrapping a monad

Question

Given the below program, I am having issues dealing with monads.

module Main 
where
import System.Environment
import System.Directory
import System.IO
import         


        

Answer 1

Use case.

main = do
    ...
    case csv_data of
        Left  err -> {- whatever you're going to do with an error -- print it, throw it as an exception, etc. -}
        Right csv -> printCSV csv

The either function is shorter (syntax-wise), but boils down to the same thing.

main = do
    ...
    either ({- error condition function -}) printCSV csv_data