hledger and hledger-ui are in haskell overlay, but I don't use haskell overlay because haskell overlay often breaks due to https://bugs.gentoo.org/555266 I ended up installing and upgrading those programs via haskell stack. I think it would be a lot better to be able to manage those programs through gentoo overlay. hledger is still actively maintained while development on ledger is stagnant.
*** This bug has been marked as a duplicate of bug 664836 ***