Add module/crate level docs

src/convert.rs

@@ -1,3 +1,5 @@
+//! Defines conversion trait between rust types and numpy data types.
+
 use ndarray::*;
 use pyo3::Python;
 

src/error.rs

@@ -1,4 +1,4 @@
-//! Define Errors
+//! Defines error types.
 
 use pyo3::*;
 use std::error;

src/lib.rs

@@ -1,3 +1,35 @@
+//! `rust-numpy` provides Rust interfaces for [numpy](http://www.numpy.org/) APIs,
+//! especially [ndarray](https://www.numpy.org/devdocs/reference/arrays.ndarray.html) class.
+//!
+//! It uses [pyo3](https://github.com/PyO3/pyo3) for rust bindings to cpython, and uses
+//! [ndarray](https://github.com/bluss/ndarray) for rust side matrix library.
+//!
+//! For numpy dependency, it calls `import numpy.core` internally so you just need numpy
+//! installed by `pip install numpy` or other ways in your python environment.
+//! You can use both system environment and `virtualenv`.
+//!
+//! # Example
+//!
+//! ```
+//! #[macro_use]
+//! extern crate ndarray;
+//! extern crate numpy;
+//! #[macro_use]
+//! extern crate pyo3;
+//! use pyo3::prelude::*;
+//! use numpy::*;
+//! fn main() {
+//!     let gil = Python::acquire_gil();
+//!     let py = gil.python();
+//!     let np = PyArrayModule::import(py).unwrap();
+//!     let py_array = array![[1i64, 2], [3, 4]].into_pyarray(py, &np);
+//!     assert_eq!(
+//!         py_array.as_array().unwrap(),
+//!         array![[1i64, 2], [3, 4]].into_dyn(),
+//!     );
+//! }
+//! ```
+
 #![feature(specialization)]
 
 #[macro_use]

src/types.rs

@@ -1,3 +1,5 @@
+//! Implements conversion utitlities.
+
 pub use num_complex::Complex32 as c32;
 pub use num_complex::Complex64 as c64;