I tried to contact Oleg Sidorkin who is the sole maintainer of eigen (https://hackage.haskell.org/package/eigen) at the stated email address (oleg dot sidorkin at gmail dot com), but received no repsonse. I also opened a GitHub issue at https://github.com/osidorkin/haskell-eigen/issues/17, asking to be a comaintainer for this package, and received no response. Furthermore, this Oleg seems to be mostly inactive on GitHub, with only two contributions over the last 12 months, the most recent one being in November of 2017.
The last version of eigen was uploaded "by OlegSidorkin at Tue Nov 7 05:53:55 UTC 2017". The haskell bindings to eigen are currently using a deprecated version of the eigen library. I have done work at the following fork: https://github.com/haskell-numerical/eigen, where I have gotten the bindings up-to-date with the most recent stable version of eigen, as well as incorporating some changes brought up by users of the library in the issue tracker and PRs of Oleg Sidorkin's GitHub repo.
I'd like to become (co-)maintainer of eigen. I have a strong interest in maintaining as well as using this library.