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Ivy

  • an AST interpreter for Vyper with a custom EVM backend

How it works

  • uses the Vyper compiler as a library
  • calls the compiler to get the annotated AST
  • an Account in the EVM doesn't contain the code, but the contract's annotated AST
  • when a tx/call is made to the contract, the AST (instead of bytecode) is interpreted
  • as in boa contracts can be deployed using load function
    • it returns a user-facing contract representation for user interaction

Run & Test

  • run: uv run python -m ivy tests/example_contracts/example.vy
  • test: uv run pytest tests
from ivy.frontend.loader import loads


def test_deploy_and_call():
    src = """
@external
def foo(a: uint256=42) -> uint256:
    return a
    """

    c = loads(src)
    assert c.foo() == 42

Implementation notes

  • the concept of gas is not supported (can't map gas costs to AST interpretation)
  • delegatecall support is basic - it's true semantics are tied to the storage layout, however, in Ivy we represent storage as a map from names to values, i.e., the concept of variable addresses is not present. It is thus impossible to map variables from the caller to the callee. Therefore, delegatecall works as expected only if the contracts have the same layout and use the same names.