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:

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.