How do I connect to a running C or C++ process / one that requires input?

[stmonty]

Hey, I have been enjoying use Dape, but I am not really an expert in debugging and the debugger adapter protocol.
One thing I have been having a hard time figuring out is how do I connect to a currently running C or C++ process?
Is this documented anywhere?

And in particular, how do you get a process to work that requires values from STDIN or some sort of input?

For example, imagine a REPL for a simple language that you could start with ./mylang repl and then type input into.

With gdb you could do something like gdb ./mylang and then gdb run repl and it will allow you to write things in the repl.

However, I am not expecting that level of functionality, but presumably if you could attach to an already running repl process, that should work?

I tried to add the :request "attach" and :pid <mylang's pid> to the minibuffer prompt after starting Dape, and then tried writing something in the repl to see if that would do anything, but it didn't seem to.

Maybe I am just fundamentally misunderstanding how this works. Any help would be appreciated!
(Also I am debugging with debug symbols).