Question

This is about syntactic sugar in Haskell. A simple Haskell program:

main = do   args <- getArgs   let first = head args   print first 

I use binding in the first line (args <- getArgs) and a pure assignment in the second one (let first = ...). Is it possible to merge them together into a readable one-liner?

I understand that I can rewrite binding “de-sugared”:

main = do   first <- getArgs >>= ( return . head )   print first 

But is there a nicer way, without cluttering the line with (>>=) and return?

Answer 1

liftM and head are all very well, but let us not forget pattern matching:

main = do { arg:_ <- getArgs; print arg } 

or if you like layout

main = do     arg : _ <- getArgs     print arg 

When possible, most Haskellers prefer pattern matching over head and tail.