roc test pa2html/main.roc
Roc application crashed with this message:

        dispatch on a value that can never exist


── ✗ fail ──────────────────────────────────────── /home/rw/media/repos/roc/plainaipha/pa2html/lib/Pa2Html.roc:18:3

expect [ ".TL Go Sleep" ] |> transform() |> List.is_eq(["<h1>Go Sleep</h1>", "<hr>"])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Ran 45 tests in 17.6 ms. (cached):
    44 passed
    1 failed
    0 compiler errors

Util :: [].{
    extract_oneliner : _, List(Str) -> _
    extract_oneliner = |prefix, lst| {
        pref = ".".concat(prefix)
        match lst {
            [first, ..] => if first.starts_with(pref) Ok(first.drop_prefix(pref).trim()) else Err(PrefixNotFound)
            _ => Err(ListHasNoHeading)
        }
    }
    expect "TL" |> extract_oneliner([".TL Hello"])? |> Str.is_eq("Hello")
    expect "TL" |> extract_oneliner([".TA Hello"]) |> Try.is_eq(Err(PrefixNotFound))
    expect "TL" |> extract_oneliner([]) |> Try.is_eq(Err(ListHasNoHeading))

    apply = |lines, functions| {
        lines_lists(lines)
            |> List.join_map(|list_list| functions.join_map(|f| f(list_list)))
    }
    expect apply(["A"], [|_| ["A"], |_| ["B"], |_| ["C"]]) |> List.is_eq(["A", "B", "C"])
    expect apply(["A"], [|a| a, |a| a]) |> List.is_eq(["A", "A"])
}

lines_lists = |input_lines| {
    aux = |lines, acc|
        match lines {
            [] => acc
            [_, .. as t] => aux(t, acc.append(lines))
        }
    aux(input_lines, [])
}

expect [1, 2, 3] |> lines_lists |> List.is_eq([[1, 2, 3], [2, 3], [3]])

Util :: [].{
    extract_oneliner = extract_oneliner
    apply = apply
}

extract_oneliner .....
appply ....