120 bench sum range foldable

~import std/io

const std = @import("std");

var input_n: u64 = 0;

~pub event read-n {}

~proc read-n|zig {
    var args = std.process.args();
    _ = args.next();
    if (args.next()) |arg| {
        input_n = std.fmt.parseInt(u64, arg, 10) catch 1_000_000;
    } else {
        input_n = 1_000_000;
    }
}

~pub event sum-range { n: u64 }
! v { item: u64, acc: u64 } -> u64
| done u64

~proc sum-range|zig {
    var acc: u64 = 0;
    for (0..n) |i| {
        acc = v(.{ .item = i, .acc = acc });
    }
    return .{ .done = acc };
}

~read-n()
~sum-range(n: input_n)
! v p -> p.acc + p.item
| done r |> std/io:print.ln("sum = {{ r:d }}")