Felix entry for "Four MLs (and a Python)"

felix.flx

fun add_to(totals: list[float])(values: list[float]) =>
    if values.len != 1.size then let n = totals.len in match n with
    | 0uz => values
    | $(values.len) => (add of (float^2)).map $ totals.zip2 values
    // this ugliness is because of a bug in Felix that generates invalid C++ code
    // see https://github.com/felix-lang/felix/issues/71
    | _ => #(fun () = { raise "Inconsistent-length rows"; return #list[float]; })
    endmatch else totals;

fun add_line_to(totals: list[float])(line: string) =>
    totals.add_to $ (float of string).map $ split (line, ',');

fun sum_file(filename: string) =>
    add_line_to.fold_left #list[float] $ split (filename.load, '\n');

proc sum_and_print_file(filename: string) {
    res := (str of float).map $ sum_file filename;
    println $ fold_left (fun (a:string)(b:string) => a+","+b) res.head res.tail;
}

match #System::args with
| Cons (_, Cons (filename, Empty)) => sum_and_print_file filename;
| _ => raise "Exactly 1 filename must be given";
endmatch;