Traefik[1] is written in Golang, which is technically a (depending on your viewpoint) memory-safe language. It has a pretty decent adoption rate, has a reasonable story for being built on battle-tested libraries, and has a pretty good reputation.
Haskell has yesod[2] but I don't think there's a variant of that dedicated to nginx- or haproxy-esque reverse proxy duties.
Traefik performance sucks... In my bench, it is like 6 times slower than haproxy on an AWS instance.
It eats up a huge amount of memory and burns all the cups....
As well, traefik configuration is not flexible enough to match haproxy power...
Haskell has yesod[2] but I don't think there's a variant of that dedicated to nginx- or haproxy-esque reverse proxy duties.
[1] https://github.com/containous/traefik
[2] https://www.yesodweb.com/