add the tutorial

demos/01_hello_world/README.md

@@ -1,35 +1,53 @@
 # 🛹 Demo 1: Hello World 
 
---
-
-### A "Hello World" Program 
 
 <br>
 
+* In a separate terminal window, start your local cluster:
 
-
-* Solana Rust programs follow the typical Rust project layout:
-
-```
-/inc/
-/src/
-/Cargo.toml
+```shell
+solana-test-validator
 ```
 
-<br>
 
 * Initialize a new Rust library via Cargo:
 
-```
+```shell 
 cargo init hello_world --lib
 cd hello_world
+cargo add solana-program
 ```
 
+* This creates a very basic Solana Rust program following this layout:
+
+```shell
+-- src/
+    |__ lib.rs
+-- Cargo.toml
+```
+
+* You should modify `Cargo.toml` to the following:
+
+```
+[package]
+name = "hello_world"
+version = "0.1.0"
+
+[lib]
+name = "hello_world"
+crate-type = ["cdylib", "lib"]
+
+[dependencies]
+// add the right version
+solana-program = "=1.1x.x"
+```
+
+
 <br>
 
-* The Rust code for Solana lives inside `src/lib.rs`. There, you import your Rust crates and define your logic.
+* We will write this program inside `src/lib.rs`. 
 
-* At the top of `lib.rs`, we import the `solana-program` crate and bring needed items into the local namespace:
+* At the top, we import the `solana-program` crate and bring needed items into the local namespace:
 
 ```rust
 use solana_program::{
@@ -44,19 +62,18 @@ use solana_program::{
 <br>
 
 * Every Solana program must define an `entrypoint` that tells the runtime where to start executing the code on-chain. 
-
-* The entry point should provide a public function named `process_instruction`:
+    - The entry point should provide a public function named `process_instruction`:
 
 ```rust
 entrypoint!(process_instruction);
 
-  pub fn process_instruction(
-   program_id: &Pubkey,
-   accounts: &[AccountInfo],
-   instruction_data: &[u8]
+pub fn process_instruction(
+   _program_id: &Pubkey,
+   _accounts: &[AccountInfo],
+   _instruction_data: &[u8]
   ) -> ProgramResult {
 
-   msg!("Solana Summer 2.0!");
+   msg!("Only possible on Solana");
 
    Ok(())
 }
@@ -65,38 +82,43 @@ entrypoint!(process_instruction);
 
 <br>
 
-* Every on-chain program should return the `Ok` result enum with value `()`. 
-  - This tells the Solana runtime that the program executed successfully.
+* Note that every on-chain program should return the `Ok` result enum with value `()`. 
+    - This tells the Solana runtime that the program executed successfully.
 
 <br>
 
 
-#### Build your program
-
+#### Build and Deploy your Program
 
 <br>
 
+* Let's build this hello world program, by running the following command from the root of the project:
+
 ```
-cargo build-bpf
+cargo build-sbf
 ```
 
-<br>
+* This command will create the compiled program's `.so` file inside a folder called `./target/deploy`:
+
+```
+find . -name '*.so'
+```
 
-#### Deploy your program:
+* Now, let's deploy it:
 
 <br>
 
 ```
-solana program deploy ./target/deploy/hello_world.so
+solana program deploy ./target/deploy/hello_world.so 
 ```
 
 <br>
 
 * When this program finishes being deployed, the program's public address (`program id`) is displayed.
 
-* To execute an on-chain program, you must send a transaction with a listing of instructions. 
-  - Each `instruction` must include all the keys involved in the operation and the program ID we want to execute.
+* You can check your Solana wallet's balance to see how much it costs to deploy this simple program.
+
+
 
 <br>
 
----