ligo lambdas & on-chain views

This repository is meant to illustrate the communication between contracts (with on-chain views) and lambda pattern which allows to modify a contract already deployed. It deals with implementing, deploying and interacting with Tezos smart contracts.

The Fund and its advisor (i.e. "L'indice et le conseiller")

The indice contract represents a fund value and the advisor contract gives an advice on investing on this fund.

Transaction workflow

Since Hangzhou protocol, on-chain views have been introduced which replace the callback pattern to retrieve information from the storage of another contract.

The executeAlgorithm entrypoint of the advisor contract requests the fund value from the indice contract (via an on-chain view). The storage of the indice contract is retrieved with a Tezos.call_view instruction inside the entrypoint of the advisor contract which can apply the "algorithm" to check if it is worth investing ! This algorithm relies on a single indice value.

The resulting advice is stored in the storage (in result field).

Lambda pattern

The real business logic of the advisor smart contract lies in the lambda function which is defined in the storage. The storage is vowed to be modified so as for the business logic (lambda).

So an entrypoint ChangeAlgorithm is provided to modify the algorithm that computes the worth of investment.

Content

This repository illustrates the new on-chain views style and contains a jsligo implementations for smart contracts and ligo command lines for simulating all entrypoints.

Pre-requisites

You need to install the following tools:

• NodeJS & Npm
• LIGO or Docker

Compiling / testing / deploying

This repository provides a Makefile for compiling and testing smart contracts. One can type make to display all available rules. The make all command will clean all produced smart contracts, then compile smart contracts and then launch tests.

• The make compile command triggers the compilation of smart contracts (advisor and indice).

• The make test command launches tests oon compiled smart contracts (advisor and indice).

• The make deploy command deploys smart contracts. You need to rename deploy/.env.dist to deploy/.env and fill the required variables.

You can also override make parameters by running :

make compile ligo_compiler=<LIGO_EXECUTABLE> protocol_opt="--protocol <PROTOCOL>"