Comment author: @dbuenzli

I overlooked the fact that both Bytes.unsafe_blit and Bytes.unsafe_blit_string are backed by the same C primitive. So Bytes.unsafe_blit_string can be written:

let unsafe_blit_string s s0 d d0 len = Bytes.(unsafe_blit (unsafe_of_string s) s0 d d0 len)

Feel free to close the PR it's not worth the hassle.

Comment author: @damiendoligez

Since we are talking about an unsafe function, I think a little verbosity is good if it makes people hesitate to use it.