There are actually 10+ independent implementations of Ethereum (including one in Haskell): https://www.reddit.com/r/ethereum/comments/3pdskt/how_many_ethereum_i

There are actually 10+ independent implementations of Ethereum (including one in Haskell): https://www.reddit.com/r/ethereum/comments/3pdskt/how_many_ethereum_implementations_are_there/ https://www.reddit.com/r/ethereum/comments/3pdskt/how_many_e... This was part of the development philosophy, to implement the client (based on the yellow paper http://gavwood.com/paper.pdf http://gavwood.com/paper.pdf that specifies the protocol) in multiple languages in order to find bugs: if 2 clients don't agree on something, then we found a bug.