Minecraft has support for a built in function called schedule that combined with code blocks could create very basic asynchronous code. Supporting the schedule command as a language feature rather than a command is mostly just syntactic sugar:

after (<time>d|s|t, replace) {
 /say hi!
}

The replace field is optional and could be a different keyword or identifier. By default though, this should compile to append rather than replace.

This would be similar to putting your code in other function and calling /schedule d|s|t , but it looks a lot nicer when you have your code in one file.