Couldn't match expected type ‘Int’ with actual type (Int, Int, Int)-CodePudding

i have a dynamic txt file example (1,1,1), im trying to read them from file to pass them to problem function.

function problem :: Int->Int->Int->[Int]

   args <- getArgs
   contents <- readFile (head args)
   let value = read contents::(Int,Int,Int)

   //print(show(problem 1 1 1))
   print(show(problem value))

Couldn't match expected type ‘Int’ with actual type ‘(Int, Int, Int)’

CodePudding user response：

You need to extract the three Int values in order to pass them individually to problem.

let (a, b, c) = read contents :: (Int, Int, Int)
print (show (problem a b c))

Conversely, you could define an uncurry3 function to adapt problem to work with a tuple.

uncurry3 :: (a -> b -> c -> d) -> ((a, b, c) -> d)
uncurry3 f = \(x,y,z) -> f x y z

print (show ((uncurry3 problem) value))