https://hirrolot.github.io/posts/rust-is-hard-or-the-misery-of-mainstream-programming.html zig code example

dispatcher.go

package main

import "fmt"

type Update struct{}
type Handler func(*Update)

type Dispatcher struct {
    handlers []Handler
}

func (dp *Dispatcher) pushHandler(handler Handler) {
    dp.handlers = append(dp.handlers, handler)
}

func main() {
    dp := Dispatcher{handlers: nil}
    dp.pushHandler(func(upd *Update) {
        fmt.Println(upd)
    })
}

dispatcher.zig

const std = @import("std");

const Update = struct {};
const Handler = fn (*Update) callconv(.Async) void;

const Dispatcher = struct {
    handlers: std.ArrayList(Handler),

    fn pushHandler(dp: *Dispatcher, handler: Handler) !void {
        try dp.handlers.append(handler);
    }
};

pub const io_mode = .evented;

pub fn main() !void {
    var gpa_instance: std.heap.GeneralPurposeAllocator(.{}) = .{};
    const gpa = gpa_instance.allocator();

    var dp = Dispatcher{
        .handlers = std.ArrayList(Handler).init(gpa),
    };
    try dp.pushHandler(struct {
        fn f(upd: *Update) void {
            std.debug.print("{}", .{upd});
        }
    }.f);
}