readme: recommend maturin init

Author: davidhewitt

README.md

@@ -24,15 +24,34 @@ You can use PyO3 to write a native Python module in Rust, or to embed Python in
 
 ### Using Rust from Python
 
-PyO3 can be used to generate a native Python module. The easiest way to try this out for the first time is to use [`maturin`](https://github.com/PyO3/maturin). `maturin` is a tool for building and publishing Rust-based Python packages with minimal configuration. The following steps set up some files for an example Python module, install `maturin`, and then show how build and import the Python module.
+PyO3 can be used to generate a native Python module. The easiest way to try this out for the first time is to use [`maturin`](https://github.com/PyO3/maturin). `maturin` is a tool for building and publishing Rust-based Python packages with minimal configuration. The following steps install `maturin`, use it to generate and build a new Python package, and then launch Python to import and execute a function from the package.
 
-First, create a new folder (let's call it `string_sum`) containing the following two files:
+First, follow the commands below to create a new directory containing a new Python `virtualenv`, and install `maturin` into the virtualenv using Python's package manager, `pip`:
+
+```bash
+# (replace string_sum with the desired package name)
+$ mkdir string_sum
+$ cd string_sum
+$ python -m venv .env
+$ source .env/bin/activate
+$ pip install maturin
+```
+
+Still inside this `string_sum` directory, now run `maturin init`. This will generate the new package source. When given the choice of bindings to use, select pyo3 bindings:
+
+```bash
+$ maturin init
+✔ 🤷 What kind of bindings to use? · pyo3
+  ✨ Done! New project created string_sum
+```
+
+The most important files generated by this command are `Cargo.toml` and `lib.rs`, which will look roughly like the following:
 
 **`Cargo.toml`**
 
 ```toml
 [package]
-name = "string-sum"
+name = "string_sum"
 version = "0.1.0"
 edition = "2018"
 
@@ -45,9 +64,8 @@ name = "string_sum"
 # crate-type = ["cdylib", "rlib"]
 crate-type = ["cdylib"]
 
-[dependencies.pyo3]
-version = "0.15.1"
-features = ["extension-module"]
+[dependencies]
+pyo3 = { version = "0.15.1", features = ["extension-module"] }
 ```
 
 **`src/lib.rs`**
@@ -67,21 +85,11 @@ fn sum_as_string(a: usize, b: usize) -> PyResult<String> {
 #[pymodule]
 fn string_sum(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(sum_as_string, m)?)?;
-
     Ok(())
 }
 ```
 
-With those two files in place, now `maturin` needs to be installed. This can be done using Python's package manager `pip`. First, load up a new Python `virtualenv`, and install `maturin` into it:
-
-```bash
-$ cd string_sum
-$ python -m venv .env
-$ source .env/bin/activate
-$ pip install maturin
-```
-
-Now build and execute the module:
+Finally, run `maturin develop`. This will build the package and install it into the Python virtualenv previously created and activated. The package is then ready to be used from `python`:
 
 ```bash
 $ maturin develop
@@ -92,7 +100,20 @@ $ python
 '25'
 ```
 
-As well as with `maturin`, it is possible to build using [`setuptools-rust`](https://github.com/PyO3/setuptools-rust) or [manually](https://pyo3.rs/latest/building_and_distribution.html#manual-builds). Both offer more flexibility than `maturin` but require further configuration.
+To make changes to the package, just edit the Rust source code and then re-run `maturin develop` to recompile.
+
+To run this all as a single copy-and-paste, use the bash script below (replace `string_sum` in the first command with the desired package name):
+
+```bash
+mkdir string_sum && cd "$_"
+python -m venv .env
+source .env/bin/activate
+pip install maturin
+maturin init --bindings pyo3
+maturin develop
+```
+
+As well as with `maturin`, it is possible to build using [`setuptools-rust`](https://github.com/PyO3/setuptools-rust) or [manually](https://pyo3.rs/latest/building_and_distribution.html#manual-builds). Both offer more flexibility than `maturin` but require more configuration to get started.
 
 ### Using Python from Rust