tl;dr

• EELS is an execution layer reference implementation in Python.
• It is updated with mainnet.
• It fills checks, and passes present ones.
• There’s an instance of an EIP carried out in EELS beneath.

Introduction

After greater than a 12 months in growth, we’re happy to publicly introduce the Ethereum Execution Layer Specification (affectionately referred to as EELS.) EELS is a Python reference implementation of the core parts of an Ethereum execution consumer targeted on readability and readability. Supposed as a religious successor to the Yellow Paper that is extra programmer pleasant and up-to-date with post-merge forks, EELS can fill and execute state checks, observe mainnet¹, and is a superb place to prototype new EIPs.

EELS offers full snapshots of the protocol at every fork—together with upcoming ones—making it a lot simpler to observe than EIPs (which solely suggest modifications) and manufacturing purchasers (which regularly combine a number of forks in the identical codepath.)

Historical past

Starting in 2021, as a challenge of ConsenSys’ Quilt staff and the Ethereum Basis, the eth1.0-spec (because it was recognized then) was impressed by the sheer frustration of getting to decipher the cryptic notation of the Yellow Paper (Determine 1) to grasp the particular habits of an EVM instruction.

Drawing on the profitable Consensus Layer Specification, we got down to create an identical executable specification for the execution layer.

Current

Immediately, EELS is consumable as a conventional Python repository and as rendered documentation. It is nonetheless a bit tough across the edges, and would not present a lot in the way in which of annotations or English explanations for what varied items do, however these will include time.

It is simply Python

Hopefully a side-by-side comparability of the Yellow Paper and the equal code from EELS can present why EELS is a precious complement to it:

def less_than(evm: Evm) -> None:
    # STACK
    left = pop(evm.stack)
    proper = pop(evm.stack)

    # GAS
    charge_gas(evm, GAS_VERY_LOW)

    # OPERATION
    consequence = U256(left < proper)

    push(evm.stack, consequence)

    # PROGRAM COUNTER
    evm.laptop += 1

Whereas Determine 2 may be digestible to lecturers, Determine 3 is indisputably extra pure to programmers.

This is a video walk-through of including a easy EVM instruction if that is your form of factor.

Writing Assessments

It bears repeating: EELS is simply common Python. It may be examined like some other Python library! Along with your complete ethereum/checks suite, we even have a collection of pytest checks.

With slightly assist from execution-spec-tests, any checks written for EELS can be utilized to manufacturing purchasers!²

Displaying Variations

Having snapshots at every fork is nice for a wise contract developer popping in to see the specifics of how an EVM instruction works, however is not very useful for consumer builders themselves. For them, EELS can show the variations between forks:

An Instance EIP

EIP-6780 is the primary EIP to get an EELS implementation supplied by the creator, Guillaume Ballet! Let’s have a look.

First, we introduce a created_contracts variable to the EVM with transaction-level scope:

 @dataclass
 class Setting:
     caller: Deal with
     block_hashes: Checklist[Hash32]
     origin: Deal with
     coinbase: Deal with
     quantity: Uint
     base_fee_per_gas: Uint
     gas_limit: Uint
     gas_price: Uint
     time: U256
     prev_randao: Bytes32
     state: State
     chain_id: U64
+    created_contracts: Set[Address]

Second, we observe which contracts have been created in every transaction:

+    evm.env.created_contracts.add(contract_address)

Lastly, we modify selfdestruct so it solely works for contracts famous in created_contracts:

-    # register account for deletion
-    evm.accounts_to_delete.add(originator)
-
+    # Solely proceed if the contract has been created in the identical tx
+    if originator in evm.env.created_contracts:
+
+        # register account for deletion
+        evm.accounts_to_delete.add(originator)
+

Future

We would like EELS to turn into the default technique to specify Core EIPs, the primary place EIP authors go to prototype their proposals, and the very best reference for a way Ethereum works.

In case you’re fascinated by contributing or prototyping your EIP, be part of us on the #specs channel or seize a problem from our repository.