std io with zig

prefix.zig

const std = @import("std");

pub fn main() !void {
    const stdout = std.io.getStdOut().writer();
    const stdin = std.io.getStdIn().reader();

    const a = std.testing.allocator;
    var buf = std.ArrayList(u8).init(a);
    defer buf.deinit();

    var args = std.process.args();

    _ = args.skip();

    var prefix = try args.next(a) orelse {
        std.debug.warn("prefix required.\n", .{});
        return;
    };

    while (true) {
        stdin.readUntilDelimiterArrayList(&buf, '\n', 1024) catch return;
        try stdout.print("{s}: {s}\n", .{ prefix, buf.items });
    }
}