> For the complete documentation index, see [llms.txt](https://gessadavide.gitbook.io/yallo-lang/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://gessadavide.gitbook.io/yallo-lang/docs/contract-interoperability.md).

# Contract interoperability

One of the key feature of yallo is the ability for contract to interact with other contracts easily. We provide a syntax for calling other contracts or deploy new one.

## Calling other contracts

The first way to call another contract is using their interface abstraction as follow; we first get the instance of an IToken (see *Contract structure* page) at a given *tokenContractAddress*. We then point to the *getBalance* entrypoint passing an address to investigate and the reference to a nat entrypoint from this contract.

```
let op: operation = IToken.of(tokenContractAddress).getBalance(addrToInvestigate, this.checkBalanceCallback); 
```

The previous code creates a operation with 0mtz inside; if we want to call another contract passing an amount, we do:

```
let op: operation = Tezos.transfer (IToken.of(tokenContractAddress).getBalance, (addrToInvestigate, this.checkBalanceCallback), 12mtz);
```

We can also get *getBalance* without using the interface IToken:

```
let getBalance: (address, nat contract) contract = Tezos.contract(tokenContractAddress, "getBalance") in
let op = getBalance(addrToInvestigate, this.checkBalanceCallback);
```

## Deploy a contract

Yallo also allow deploying a contract from another contract. For instance, we can deploy the *Token* contract from another contract:

```python
import "test/contract/token.yallo";

contract deployAToken {
	field tokenAddress: address;

	entry deployToken() {
		let (op: operation, a: address) = Tezos.createContract (Token(100, "ourToken"), None, 0mtz);
		this.tokenAddress = a;
		[op]
	}
}
```

We use the constructor of Token to produce the initial storage.