What types of smart contracts are available for bitcoin network in 2021?

Question

We all know that the first smart contracts appeared on the Ethereum network. As far as I know, in the Bitcoin network, smart contracts work with a limited functionality – Bitcoin uses a non-Turing Complete language. At the moment, just the following types of smart contracts are possible on the bitcoin network:

• Endowment contract
• Escrow contract
• Will of digital assets
• Multisig contract
• Safe for digital assets
• etc...

Questions:

1. What other types of contracts can I implement in 2021?

2. What languages ​​are mainly used to implement smart contracts in the network?

3. Can you give an example of an implemented smart contract in Apple Swift language?

Answer 1

We all know that the first smart contracts appeared on the Ethereum network. As far as I know, in the Bitcoin network, smart contracts work with a limited functionality.

These two sentences are contradictory. If Bitcoin has smart contracts with limited functionality, they cannot be the first on some other network. A smart contract with less functionality is still a smart contract.

Bitcoin uses a non-Turing Complete language

Answered in detail here: https://bitcoin.stackexchange.com/a/105931/

What other types of contracts can I implement in 2021? What languages ​​are mainly used to implement smart contracts in the network?

Old answer but still relevant: https://bitcoin.stackexchange.com/a/53843/

Other things:

1. Lightning Network is the biggest example of a smart contract live on Bitcoin

2. Taproot and future soft forks will further improve scripting capabilities but according to my understanding it will never be same as "World Computer" meme and do everything on-chain. Layer 2 works better for decentralized networks considering scaling, security etc.

3. Rootstock (sidechain) allows everything that is possible on Ethereum with better scaling, privacy etc.

   https://bitcoin.stackexchange.com/a/103169/

4. Liquid (sidechain) works differently and allows devs, users, exchanges etc. to experiment with lot of projects.

   https://blog.liquid.net/six-differences-between-liquid-and-lightning/

   Parallel processing in a UTXO model: https://medium.com/bit-matrix/how-does-bitmatrix-achieve-parallel-processing-in-a-utxo-model-6ef70141bd59

5. If projects require oracle, discreet log contracts can be used: https://github.com/discreetlogcontracts/dlcspecs