#moon_evmasm

moon_evmasm is a MoonBit Ethereum EVM assembler/disassembler library, ported from the Python project pyevmasm.

This package is library-only. It does not include a CLI layer.

#What it provides

Fork-aware opcode tables from frontier to osaka
Assemble APIs:
- assemble_one
- assemble_all
- assemble
- assemble_hex
Disassemble APIs:
- disassemble_one
- disassemble_all
- disassemble
- disassemble_hex
Fork helpers:
- accepted_forks
- default_fork
- instruction_table_for_fork
- block_to_fork
Structured error type: EvmError

#Quick example

// import path in this repo:
// @caimeo/moon_evmasm/src

let insn = assemble_one("PUSH1 0x10")
assert_eq(insn.mnemonic(), "PUSH1")

let bytecode_hex = assemble_hex("PUSH1 0x80\nMSTORE")
assert_eq(bytecode_hex, "0x608052")

let asm = disassemble_hex("0x60804052")
assert_eq(asm, "PUSH1 0x80\nBLOCKHASH\nMSTORE")

let fork = block_to_fork(17034870)
assert_eq(fork, "shanghai")

Error handling example:

let result = try! assemble_one("PUSH1")
assert_true(result is Err(MissingOperand(_)))

#Development

Run checks and tests from the module root:

moon -C moon_evmasm check
moon -C moon_evmasm test

Current status (2026-02-09):

Core functionality is implemented
Fork tables are enum-based internally (not stringly typed)
Migrated test suite is passing (32 tests)

#License

Apache-2.0. See LICENSE.

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