Huff Langugage / huff-neo - Documentation

There is huff-rs and huff-neo?

Yes, there are two versions of the Huff compiler. The original compiler, huff-rs is no longer maintained. There is a plan to revive it as huff2, but since it is a new development from scratch, it is unknown when it will have feature parity with the original compiler. huff-neo tries to step-in and continues the development and also tries to evolve the Huff language where necessary.

New in huff-neo

There are some new features in huff-neo that are not available in huffc.

Allowed use of built-in functions for constants and code tables

The usage of built-in functions for constants and code tables is now possible.

#define constant FUNC_TEST = __FUNC_SIG("test(uint256)")
#define constant BYTES_HELLO = __BYTES("hello")

#define code_table TEST_TABLE {
    0x123
    __FUNC_SIG("test(uint256)")
    __BYTES("hello")
    __LEFTPAD(__FUNC_SIG("test(uint256)")) // New built-in function __LEFTPAD
    [FUNC_TEST]
    [BYTES_HELLO]
}

New built-in functions

There are new built-in functions available in huff-neo.

• __LEFTPAD - Left pads a hex input or the result of a passed built-in in a code table.
• __BYTES - Converts a string to the UTF-8 representation bytes and pushes it to the stack.

#define macro MAIN() = takes (0) returns (0) {
    __BYTES("hello") // Will push UTF-8 encoded string (PUSH5 0x68656c6c6f)
}

New test capabilities

The test module has been refactored to use anvil and forge features from foundry to fork the mainnet. This allows for more advanced testing capabilities.