--Did you go to see the film Let Go Bullets last night?
--Yes. So I did.
Is the Yes in the reply necessary? I would think using 'So I did' or just 'Yes, I did' would be ok. But I'd like to know whether many native English speakers use 'Yes. So I did.' in such a context.
Thank you in advance.
Not many, but some. This may have something to do with the fact that Latin had no single word for 'yes' so many translations introduced a 'so' on the basis of something like ita vero ('thus indeed'), and many older prescriptive grammars 'followed suit' [='adopted the same approach'].
Tangentially, it was on the basis of the Latin etiam that most Romance languages introduced the particle 'si'.