American Sign Language is not a simple mapping of signs to English or any other spoken/written language. OTOH, Signed Exact English is that, which is why for pedagogical reasons, e.g., teaching deaf kids written English, it is championed in US schools, and also why the deaf community shuns it. ASL has its own unique grammar. I have discussed this with linguists, deaf people who sign, and some who are an intersection of both groups.

Ceci n'est pas un seing.