I definitely agree copilot isn't understanding the problem space of your code. But I also don't believe it's simply remixing code samples from its training set.

I definitely agree copilot isn't understanding the problem space of your code. But I also don't believe it's simply remixing code samples from its training set. It's somewhere in between. I don't know the internals, but it looks to me like it's operating at a few layers of abstraction over literal code and syntax. It find patterns in the relationships between symbols and references. Not to mention since it's GPT-3 based, it's cross referencing the "meaning" in these abstract relationships with the meaning of plain English text written in comments, too. These pieces are similar to humans. Just like a human, copilot doesn't have a ton of exact literal code in its model. It's seen lots of code and has patterns and relationships in its model. That's why just like a human, it can translate ideas between different coding languages -- my guess would be it can write an algorithm its seen in C in F# even if its never seen that algorithm in F#; but that's hard to prove. Just like a human though, it might have some literal snippets, though. It can definitely translate between languages ; I've done that a few times. (It can even translate human languages eg English to French! I've done that sometimes for fun) I would highly recommend giving the trial version a go, if only to better understand how it works. Whether it "understands" eg a map operation... That's hard to prove. Can you think of any experiments? I think it understand the relationship between the English word map and the code patterns often associated with that word. I think your example is close. Copilot is a lot like an inexperienced developer. It doesn't (usually) make syntax errors, but because it doesn't understand your problem space, and because it doesn't have as many layers of abstraction as a human does, it does sometimes make silly mistakes. I definitely wouldn't trust it to write an entire program on its own! But with a human in the loop doing the more complicated abstract pieces of coding, it handles the more simple menial pieces pretty well!