Hello World - Compile and Run

module Main

  data Tree a = Leaf
              | Node (Tree a) a (Tree a)

  inorder : Tree a -> List a
  inorder Leaf = []
  inorder (Node left a right) = inorder left ++ [a] ++ inorder right

  tree : Tree String
  tree = Node
          (Node
            (Node Leaf "3" Leaf)
            "+"
            (Node Leaf "7" Leaf))
          "/"
          (Node Leaf "2" Leaf)

  main : IO ()
  main = printLn $ inorder tree

Compile

idris2 helloworld.idr -o main

Run

% build/exec/main
["3", "+", "7", "/", "2"]