A friend writes:
As a meta-observation, one of the reasons I enjoy writing to you so much is that I can use my inner language — which is a mixture of Russian and English. There is something very interesting (to me) in my code switching practice: when the switch occurs in the middle of the sentence, the resulting output has to be valid in both grammars. How my brain does that is the real question — do you know any book that deals with it?
I do not, and it’s an interesting question, so I pass it along to my readership. If you know of any good articles accessible via JSTOR, they’re welcome too.