Migration: CSL to Pallas

This guide covers migrating from the legacy cardano-serialization-lib (CSL) backend to the pallas-based backend.

Why Migrate?

Both serialization libraries have similar functionality, but Pallas offers:

• Better maintenance — actively updated for Cardano hard forks
• Pure Rust — no C/WASM dependencies
• Ecosystem alignment — used widely in the Cardano Rust ecosystem

The whisky main crate now defaults to Pallas. CSL has been removed from the default feature set.

Transaction Building

Before (CSL)

use whisky::*;
use whisky_csl::WhiskyCSL;

let mut tx_builder = TxBuilder::new(TxBuilderParam {
    serializer: Box::new(WhiskyCSL::new(None)),
    evaluator: None,
    fetcher: None,
    submitter: None,
    params: None,
});

After (Pallas)

use whisky::*;
use whisky_pallas::WhiskyPallas;

// Option 1: Explicit
let mut tx_builder = TxBuilder::new(TxBuilderParam {
    serializer: Box::new(WhiskyPallas::new(None)),
    evaluator: None,
    fetcher: None,
    submitter: None,
    params: None,
});

// Option 2: Use the convenience constructor (defaults to Pallas)
let mut tx_builder = TxBuilder::new_core();

The transaction building API remains identical — only the serializer instantiation changes:

let signed_tx = tx_builder
    .tx_in(tx_hash, tx_index, amount, address)
    .change_address(my_address)
    .signing_key(skey_hex)
    .complete_sync(None)?
    .complete_signing()?;

Transaction Parsing

Before (CSL)

use whisky_csl::CSLParser;

let mut parser = CSLParser::new();
parser.parse(tx_hex, &utxos)?;
let body = parser.get_builder_body();

After (Pallas)

use whisky_pallas::tx_parser::parse;

let body = parse(tx_hex, &utxos)?;

Or using the trait-based approach:

use whisky_pallas::tx_parser::PallasParser;
use whisky_common::TxParsable;

let mut parser = PallasParser::new();
parser.parse(tx_hex, &utxos)?;
let body = parser.get_builder_body();

Transaction Evaluation

use uplc::tx::script_context::SlotConfig;
use whisky_common::{Network, UTxO};
use whisky_pallas::utils::evaluate_tx_scripts;

let result = evaluate_tx_scripts(
    tx_hex,
    &utxos,
    &[],                      // additional chained transactions
    &Network::Mainnet,
    &SlotConfig::default(),
);

Dependency Changes

If you were depending on whisky-csl directly, update your Cargo.toml:

Before

[dependencies]
whisky = "1.0.17"
# CSL was included by default

After

[dependencies]
whisky = "1.0.28-beta.1"
# Pallas is now the default — no extra dependency needed

# Only if you still need CSL:
# whisky-csl = "1.0.28-beta.1"

Summary of Changes

The transaction building API (tx_in, tx_out, change_address, complete, etc.) is unchanged — migration only requires swapping the serializer backend.