[josephlord]

But it would be unable to interact in a symbolic way with the calling app. It might be able to access things in frameworks but it might as well be a separate app that you compile with external tools at that point.

As to why it couldn't interact with the running app others have given some examples but it couldn't even reliably call functions as they may be inlined or generics may only be compiled into their required type specific versions.

I do expect[0] Apple to open source Swift when it is finally released and it to be part of the LLVM project so you could embed whatever parts make sense in your own applications but it wouldn't be like an eval function as I understand it although you could probably use it to make your own playground system. Basically it would be an LLVM feature/library not a Swift language feature.

[0] Guess. I have no inside information and may end up disappointed.