Update: Looks like the related HN discussion is here:
"Nilang.jl – A Reversible Julia DSL":
https://news.ycombinator.com/item?id=24743813
https://github.com/GiggleLiu/NiLang.jl
(Worth it, in my opinion, for the chart showing the "reversed-functions/variables" preceeded by '∂', i.e., ∂x, ∂y, ∂sqxN, etc.)
But anyway, NiLang definitely looks interesting!