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Tutorial 0: A Minimal Example

Here, we introduce a minimal example demonstrating the Anchor workflow and core syntax elements. This tutorial assumes all prerequisites are installed and a local network is running.

Clone the Repo

To get started, clone the repo.

git clone https://github.com/project-serum/anchor

And change directories to the example.

cd anchor/examples/tutorial/basic-0

Defining a Program

We define the minimum viable program as follows.

<<< @/../examples/tutorial/basic-0/program/src/lib.rs

#[program] First, notice that a program is defined with the #[program] attribute, where each inner method defines an RPC request handler, or, in Solana parlance, an "instruction" handler. These handlers are the entrypoints to your program that clients may invoke, as we will see soon.
Context<Initialize> The first parameter of every RPC handler is the Context struct, which is a simple container for the currently executing program_id generic over Accounts--here, the Initialize struct.
#[derive(Accounts)] The Accounts derive macro marks a struct containing all the accounts that must be specified for a given instruction. To understand Accounts on Solana, see the docs. In subsequent tutorials, we'll demonstrate how an Accounts struct can be used to specify constraints on accounts given to your program. Since this example doesn't touch any accounts, we skip this (important) detail.

Building and Emitting an IDL

After creating a program, one can use the anchor CLI to build and emit an IDL, from which clients can be generated.

anchor build

::: details The build command is a convenience combining two steps.

cargo build-bpf
anchor idl -f src/lib.rs -o basic.json. :::

Once run, you should see your build artifacts, as usual, in your target/ directory. Additionally, a basic.json file is created. Inspecting its contents you should see

{
  "version": "0.0.0",
  "name": "basic",
  "instructions": [
    {
      "name": "initialize",
      "accounts": [],
      "args": []
    }
  ]
}

From which a client can be generated. Note that this file is created by parsing the src/lib.rs file in your program's crate.

::: tip If you've developed on Ethereum, the IDL is analogous to the abi.json. :::

Deploying a program

Once built, we can deploy the program using the solana deploy command.

solana deploy <path-to-your-repo>/anchor/target/deploy/basic_program_0.so

Making sure to susbstitute paths to match your local filesystem. Now, save the address the program was deployed with. It will be useful later.

Generating a Client

Now that we have an IDL, we can use it to create a client.

<<< @/../examples/tutorial/basic-0/app/client.js#main

Notice how the program dynamically created the initialize method under the rpc namespace.

Next Steps

So far we've seen the basics of how to create, deploy, and make RPCs to a program on Solana using Anchor. But a program isn't all that interesting without interacting with it's peristent state, which is what we'll cover next.

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