I wasn't referring to zk-snarks.
Were you referring to CryptoNote ring sigs then?

LOL.
No. I'm referring to ShadowCash's unique ZK anon implementation (which makes use of ring sig as well as other tech) as explained in this whitepaper. The code is currently being reviewed by Isidor Zeuner.
ShadowCash: Zeroknowledge Anonymous Distributed ECash
via Traceable Ring Signatures http://shadow.cash/downloads/shadowcash-anon.pdf