Ethereum Execution Layer Specification | Ethereum Basis Weblog







  • EELS is an execution layer reference implementation in Python.
  • It is up-to-the-minute with mainnet.
  • It fills checks, and passes present ones.
  • There may be an instance of an EIP applied in EELS beneath.


After greater than a yr in building, we are happy to publicly introduce the Ethereum Execution Layer Specification (affectionately referred to as EELS.) EELS is a Python reference implementation of the core elements of an Ethereum execution shopper concerned about clarity 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, apply mainnet1, and is a brilliant position to prototype new EIPs.

EELS supplies whole snapshots of the protocol at each and every fork—together with upcoming ones—making it a lot more uncomplicated to apply than EIPs (which handiest suggest adjustments) and manufacturing purchasers (which continuously combine a couple of forks in the similar codepath.)

Historical past

Starting in 2021, as a undertaking of ConsenSys’ Cover staff and the Ethereum Basis, the eth1.0-spec (because it used to be identified then) used to be impressed via the sheer frustration of getting to decipher the cryptic notation of the Yellow Paper (Determine 1) to know the precise conduct of an EVM instruction.

Screenshot of formulas 2, 3, and 4 from the Yellow Paper
Determine 1. arcane runes describing the root of the blockchain paradigm

Drawing at the a success Consensus Layer Specification, we got down to create a equivalent executable specification for the execution layer.


Lately, EELS is consumable as a conventional Python repository and as rendered documentation. It is nonetheless a little bit tough across the edges, and does not supply a lot in the best way of annotations or English explanations for what more than a few items do, however the ones will include time.

It is simply Python

Confidently a side-by-side comparability of the Yellow Paper and the identical code from EELS can display why EELS is a precious supplement to it:

Less-than (LT) opcode

Determine 2. Much less-than (LT) EVM instruction from Yellow Paper

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

    # GAS
    charge_gas(evm, GAS_VERY_LOW)

    outcome = U256(left < proper)

    push(evm.stack, outcome)


Determine 3. Much less-than (LT) EVM instruction from EELS

Whilst Determine 2 may well be digestible to teachers, Determine 3 is unquestionably extra herbal to programmers.

Here is a video walk-through of including a easy EVM instruction if that is your more or less factor.

Writing Exams

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

With just a little assist from execution-spec-tests, any checks written for EELS will also be carried out to manufacturing purchasers!2

Appearing Variations

Having snapshots at each and every fork is superb for a sensible contract developer popping in to look the specifics of ways an EVM instruction works, however is not very useful for shopper builders themselves. For them, EELS can show the diversities between forks:

Screenshot of the differences in the apply_fork function between homestead and the DAO fork

Determine 4. one distinction between home and the DAO fork

An Instance EIP

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

Screenshot of EIP-6780's specification section

Determine 5. EIP-6768’s specification phase

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

 elegance Setting:
     caller: Deal with
     block_hashes: Checklist[Hash32]
     beginning: 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]

2d, we be aware which contracts had been created in each and every transaction:

+    evm.env.created_contracts.upload(contract_address)

After all, we change selfdestruct so it handiest works for contracts famous in created_contracts:

-    # sign up account for deletion
-    evm.accounts_to_delete.upload(originator)
+    # Simplest proceed if the contract has been created in the similar tx
+    if originator in evm.env.created_contracts:
+        # sign up account for deletion
+        evm.accounts_to_delete.upload(originator)

Long run

We would like EELS to transform the default strategy to specify Core EIPs, the primary position EIP authors cross to prototype their proposals, and the most efficient imaginable reference for a way Ethereum works.

In case you are thinking about contributing or prototyping your EIP, sign up for us at the #specs channel or grasp a topic from our repository.

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