Why iota coin do not support smart-contracts?

Question

I thought that Iota-coin have a lot of common with Ethereum, but I hae found that it do not have support of smart-contracts. I googled about what was there reason of do not implement it (I really thought that smart contracts is future) but I found only one mention about it:

"Iota itself cannot implement smart contracts cause there is no consensus on state finality and each node has its own personal view of the state, rendering unusable for distributed general purpose computation."

Does smart-contracts have any issues? Or What?

Answer 1

IOTA is very different from Bitcoin. Consensus formation and transactions are not separate. In Bitcoin you have miners that realize consensus on the order of transactions, that are separate from the transactions done. In IOTA every transaction has to validate two earlier transactions. This leads to another data structure than a blockchain, they call the Tangle:

A "blockchainless blockchain".

Now, to implement a virtual machine that can execute a smart contract it needs to have consensus on order of transactions (let's say, the order of "0"s and "0"s). With the Tangle every node has a different view of when transactions happened. This makes it impossible to have consensus on smart contracts.

Facilitating smart contracts is on the roadmap of IOTA. The idea is to do this with timestamp oracles that provide a mechanism for order of transactions. See [http://iota.org/timestamps.pdf](On the timestamps in the tangle).