roc-stuff/fib.roc

app "fibonacci"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.1/Icc3xJoIixF3hCcfXrDwLCu4wQHtNdPyoJkEbkgIElA.tar.br" }
    imports [pf.Stdout, pf.Task]
    provides [main] to pf

main : Task.Task {} I32
main =
    numStrings =
        List.range { start: At 0u128, end: At 186u128 } # 186 is all we can do with 128 bit
        |> List.walk [] fibWalk
        |> List.map Num.toStr
        |> Str.joinWith "\n"

    Stdout.line "$(numStrings)"

fibWalk : List (Num a), Num a -> List (Num a)
fibWalk = \l, n ->
    next =
        when l is
            [] | [_] -> fib n
            [.., a, b] -> a + b
    List.append l next

fib : Num a -> Num a
fib = \n ->
    if n < 2 then
        n
    else
        fib (n - 1) + fib (n - 2)