Ethereum Execution Layer Specification | Ethereum Foundation Blog

tl;dr

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

Introduction

After greater than a yr in improvement, we’re happy to publicly introduce the Ethereum Execution Layer Specification (affectionately often known as EELS.) EELS is a Python reference implementation of the core elements of an Ethereum execution shopper targeted on readability and readability. Meant 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 good place to prototype new EIPs.

EELS gives 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 venture of ConsenSys’ Quilt crew and the Ethereum Basis, the eth1.0-spec (because it was identified then) was impressed by the sheer frustration of getting to decipher the cryptic notation of the Yellow Paper (Figure 1) to grasp the particular conduct 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

At present, EELS is consumable as a traditional Python repository and as rendered documentation. It is nonetheless a bit tough across the edges, and does not present a lot in the best way of annotations or English explanations for what numerous 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 helpful 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
    end result = U256(left < proper)

    push(evm.stack, end result)

    # PROGRAM COUNTER
    evm.computer += 1

Whereas Figure 2 could be digestible to lecturers, Figure 3 is indisputably extra pure to programmers.

This is a video walk-through of adding a simple EVM instruction if that is your sort of factor.

Writing Assessments

It bears repeating: EELS is simply common Python. It may be examined like another Python library! Along with all the ethereum/tests suite, we even have a number of pytest checks.

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

Displaying Variations

Having snapshots at every fork is nice for a sensible contract developer popping in to see the specifics of how an EVM instruction works, however is not very useful for shopper 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 offered 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: Handle
     block_hashes: Listing[Hash32]
     origin: Handle
     coinbase: Handle
     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 notice which contracts had 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 wish EELS to turn out to be the default technique to specify Core EIPs, the primary place EIP authors go to prototype their proposals, and the very best reference for the way Ethereum works.

In the event you’re considering contributing or prototyping your EIP, be part of us on the #specifications channel or seize a problem from our repository.