Macro app 

macro_rules! app {
    () => { ... };
}

This macro is used to setup the Mopro FFI library It should be included in the lib.rs file of the project

This should be used with the adapter-specific macros, such as set_circom_circuits!(...) and set_halo2_circuits!(...), etc.

Circom Example

// Setup the Mopro FFI library
mopro_ffi::app!();

// Generate a Witness Generation function for the `multiplier2` circom circuit
rust_witness::witness!(multiplier2);

// Add `multiplier2` circom circuit to be exposed to the FFI
mopro_ffi::set_circom_circuits!(
    "multiplier2_final.zkey",
    WitnessFn::RustWitness(multiplier2_witness),
)

Halo2 Example

// Setup the Mopro FFI library
mopro_ffi::app!();

// Add `Fibonacci` circuit to generate proofs and verify proofs
mopro_ffi::set_halo2_circuits!(
    "plonk_fibonacci_pk.bin",
    plonk_fibonacci::prove,
    "plonk_fibonacci_vk.bin",
    plonk_fibonacci::verify
);

Noir Example

Noir integration supports two hash functions for different use cases:

• Poseidon hash: Default choice, optimized for performance and off-chain verification
• Keccak256 hash: Required for Solidity verifier compatibility and on-chain verification

The hash function is automatically selected based on the on_chain parameter:

• on_chain = false → Uses Poseidon (better performance)
• on_chain = true → Uses Keccak256 (Solidity compatible)

Reference: https://noir-lang.org/docs/how_to/how-to-solidity-verifier

You don’t need to generate Witness Generation functions first, like Circom or Halo2 does. All you need to do is to setup the Mopro FFI library as below.

// Setup the Mopro FFI library
mopro_ffi::app!();