That's not really how Dark works. You're not manipulating text in your editor - you use our editor, and our editor only uses ASTs. So when cutting and pasting, you're cutting and pasting AST, not text. So to answer your question, you can paste an entire handler or function at once, but it will be one you copied from another place in DArk and it will be structured.

We've looked at allowing people to paste text (eg from Stackoverflow) into Dark. We think we can do it by just inserting each character one at a time (though there's a technical flaw with that at the moment, which could be addressed). In that sense, Dark is sort-of a parser (I don't know if it technically counts).