Idris2/tests/idris2/coverage010/casetot.idr

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Idris
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module Main
import Data.Strings
import Data.Vect
import System
%default total
ints : Vect 4 Int
ints = [1, 2, 3, 4]
main : IO ()
main = do
[_, arg] <- getArgs
| _ => do putStrLn "One argument expected."
exitFailure
let n = stringToNatOrZ arg
case natToFin n (length ints + 1) of
Nothing => do putStrLn "Invalid number."
exitFailure
Just (FS i) => putStrLn $ "Value: " ++ show (index i ints)