How to check if a bash command has been executed successfully

Question

I'm trying to make a little program in Haskell. What I need to do is to check if a bash command has been executed successfully by the Haskell interpreter. Let's say in "pseudocode":

  $import System

  $if( system "ls" ) has been succesfully run 
  $then doStuff

How would you write this piece of code in Haskell?

Answer 1

You can do this:

import System

main = do
  result <- system "ls"
  case result of
    ExitSuccess ->
      putStrLn "Ran successfully"
    ExitFailure code ->
      putStrLn $ "Failed with exit code " ++ show code