sol.tty

What it does

The scripting layer Ethereum was missing. A Solidity implementation of the EVM deployed as an Identity contract so you can run any Solidity code just like you could if you had a REPL.

Sol.tty is an easy way to script multiple transaction calls together and send them in a single transaction.

Ideal for saving gas by batching transactions together, writing one-off scripts and codifying specific transaction behavior in a reusable format.

How we built it

There are a couple of steps involved in making this:

• A factory contract that
  • Acts as a registry where we map wallet addresses to Identity contracts
  • Deploys new identity contracts if needed
• Identity contract that
  • Has a full implementation of the EVM (bytecode parsing and OP code evaluation)
  • Accepts bytecode and a function selector and passes it to the EVM implementation to be executed
• Use solcjs on the front-end app to compile the snippet into bytecode
• Sending the compiled bytecode to the Identity contract

Challenges we ran into

• Implementing the EVM itself (all of the OP codes) while keeping the gas usage low

Accomplishments that we're proud of

• Implementing the EVM inside the EVM
• Our own Stack implementation used by our embedded VM
• The idea of writing an on-chain REPL

What we learned

• Some of the internals of the EVM itself

Links

• GitHub Repository
• Deployed EvalFactory on Kovan

Demo

Built With

• assembly
• ethereum
• evm
• javascript
• react
• solidity