Example:
let fib = (x) =>
if x == 1 then 1 else
if x == 2 then 1 else
add(app(fib, add(x, -1)), app(fib, add(x, -2))) in
app(fib, 8)
yields 21.
Main.scala has a main function run that reads file from file system.
Lib.scala has a library function run that interprets a given string.