We Cannot and We Shall Not

FROM CHARLIE

I've done the requisite Googling - which favors "cannot" except for a few particular situations, but it just looks wrong to me. Opinions?

What is your opinion re use of I shan't/I shall not? Just curious.

RESPONSE

I separate “cannot” only if I need to emphasize either part:

I know Robert's spread himself a little thin, but he CAN not attend the party. Then he could rest.
Robert can NOT attend the party; it's simply unacceptable.

Otherwise, it's one word.

I would use "shan't" if I wanted a modern character to appear pretentious or affected and "shall not" for solemnity or resolve. That's just off the top of my head; I don't use either very much.