Bitcoin Cash is programmable money, this means developers can write smart contracts which are more complex than a normal spending transaction. Multi-Signature wallets are the simplest example of smart contracts but clever finance or recurring payment applications can also be written! The notable team working on BCH smart contracts, more specifically DeFi, is General Protocols, they developed the Anyhedge smart contracts which enables onchain future contracts. An exciting usecase of AnyHedge is that it allows merchants to stabilize the value of their BCH without having to sell for trusted stablecoins. Their protocol and smart contract is usable by anybody but they made it into a end-user product themselves with BCH Bull. The AnyHedge functionality however is more general and has been integrated in the Paytaca Wallet recently. Other smart contract applications on BCH include the inheritance contract Last Will & the recurring payment contract Mecenas both by Licho, a social gambling game RefreshTimer.cash as well as the recently retired non-custodial escrow by Local Cryptos.
The promise of DeFi
"DeFi" or Decentralized Finance means financial applications without middlemen. It's a different paradigm that levels the playing field by removing barriers to entry and, because there are no middlemen, is non-custodial. The non-custodial nature of DeFi applications provides an incentive for cryptocurrency holders to withdraw from an exchange to take part in them. These finance applications increase the liquidity a cryptocurrency and can use the speculative climate of the cryptospace to offer useful hedging contracts to merchants for example. Currently the most popular DeFi applications are automated market makers, algorithmic stablecoins and borrowing & lending applications. There is a lot a room for growth, with sythetic assets on a decentralized network traditional finance products like stocks would be tradeable without the limits of legacy finance. The execution of DeFi smart contracts is trustless but outside datasources called oracles are often required to provide (price) data to the blockchain. The need to trust an oracle is the Achilles' heel in smart-contract construction and requires reliance on reputation.
Solutions like Bitcoin Hivemind introduce decentralized oracles corporations.
Advantages of BCH
Bitcoin Cash has undergone multiple hard fork upgrades which expanded its smart contract capabilites, most important of which are the native introspection opcodes to create covenants, the opcode "checkdatasig" to enable the verification of oracle data, the change to 64bit integers and the re-enabling of opcodes like OP_MUL and OP_CAT. Together these enable complex smart contracts which are not possible on BTC. Compared to more powerful smart contract blockchains like ETH, Bitcoin Cash has the advantage of using a UTXO model while ETH has an account based model with a global state. Put simply this means BCH scales much much better than the ETH architecture so it will not have the same fee problem with increased usage. Complex decentralized applications such as ICOs, DOAs, AMM-style DEXes and sidechains are now all technically possible due to the Cashtokens upgrade of May 2023.
To get a better idea of the difference in smartcontract capabilities read: "Smart contracts on Ethereum, Bitcoin and Bitcoin Cash".
"BCH Bull", is the in-house project by the General Protocols team that uses their AnyHedge smart contract. The AnyHedge smart contract in principle allows BCH denominated futures on any asset with an oracle price feed. The BCH Bull production release was on April 17th and now it lists 6 different assets for users to long or hedge against. Hedging your BCH against your local currency pair stabilizes its value without having to sell for trusted stablecoins. BCH Bull falls under the umbrella term "DeFi" because it is a non-custodial finance application. The website of the BCH Bull website is bchbull.com, and the non-custodial app is at app.bchbull.com.
There is a great independent video explaining the mechanisms behind the anyhedge contract " How AnyHedge works".
May 2023 upgrade
The latest upgrade has continued this focus on the smart contract capabilites of Bitcoin Cash. The most important CHIP for
the May 2023 upgrade has been Cashtokens!
As the name suggests, the CHIP enables native tokens on BCH (both fungible and non-fungible)
which means the tokens are scalable and consensus validated just as BCH itself and unlike layer-2 token systems such as SLP.
But importantly Cashtokens also enables contract-verifiable messages for onchain applications which is improvement to the scripting system yet!!
To demonstrate the capabilities of the proposal the author, Jason Dreyzehner, made a full proof of concept implementation of a DEX,
a decentralized exchange which runs fully onchain! The Jedex smart contract follows a modular approach so it consists of 8 separate
smart contracts. Because of this it does not run into the rather strict VM limits for smart contracts in terms of opcodes and bytesize.
Cashtokens has been the biggest upgrade for BCH to-date and makes Bitcoin Cash the most advanced UTXO-based smart contract blockchain!
There were three other minor improvements included May 2023 namely upgrading P2SH to 32bytes (instead of just 20 bytes)
to mitigate hash collision attacks, making correct use of transaction version a consensus rule
and lastly allowing transactions smaller than 64 bytes.
The specifics of the improvement proposals (CHIPs) can be found on the Bitcoin Cash research forum. Some prominent ideas for the future to extend this focus on smart contract features to enable complex and scalable decentralized applications on Bitcoin Cash include enabling bounded loops and redesigning the virtual machine limits to get rid of the 201 opcode limit and of the 520 bytesize limit for smart contract developers.
A major driver for the Castokens proposal is that it enables "Prediction Markets on Bitcoin Cash".
Decentralized prediction markets have the potential to be one of the most important innovations in the cryptocurrency space.