======
# returns an unused procedure name
proc gensym {prefix} {
    tailcall apply {{prefix} {
        string cat $prefix[llength [info commands $prefix*]]
    }} $prefix
}
 
# creates an anonymous coroutine
proc go {cmd args} {
    set name [gensym goro#]
    coroutine $name $cmd {*}$args
    return $name
}
======

Credit for the above code goes to [aspect].

The odd construct with `tailcall apply` is so that [info commands] will be executed in the caller's namespace.

[MS] finds that this construct has a big problem: name reuse. Some code could be holding onto a coro handle, and wanting to find out if it still exists via [[info command]] (or just waiting to error out, intentionally or not). If the coro exited and a new one was created with the same name, chaos could ensue ...

So my proposal is to either use a global counter (possibly in a namespace). If we really cannot live with a global var, we could do:

======
coroutine gensym apply [list prefix {
    while 1 {
        yield $prefix[incr counter]
    }
}
======

<<categories>>Concurrency