Anonymous recursive functions (use recur)

In Slug, you don’t need to name a function to make it recursive. The recur keyword allows an anonymous function to call itself.

var factorialResult = fn(n, acc = 1) {
    if (n <= 1) {
        acc
    } else {
        recur(n - 1, n * acc)
    }
}(5)

println("factorial(5)", factorialResult) // 120