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| -rw-r--r-- | dhall/src/lib.rs | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/dhall/src/lib.rs b/dhall/src/lib.rs index 2d44115..ababc5d 100644 --- a/dhall/src/lib.rs +++ b/dhall/src/lib.rs @@ -9,6 +9,112 @@ clippy::many_single_char_names )] +//! [Dhall][dhall] is a programmable configuration language that provides a non-repetitive +//! alternative to JSON and YAML. +//! +//! You can think of Dhall as: JSON/YAML + types + imports + functions +//! +//! For a description of the dhall language, examples, tutorials, and more, see the [language +//! website][dhall]. +//! +//! This crate provides support for consuming dhall files the same way you would consume JSON or +//! YAML. It uses the [Serde][serde] serialization library to provide drop-in support for dhall +//! for any datatype that supports serde (and that's a lot of them !). +//! +//! This library is limited to deserializing (reading) dhall values; serializing (writing) +//! values to dhall is not supported for now. +//! +//! # Examples +//! +//! ### Custom datatype +//! +//! If you have a custom datatype for which you derived [serde::Deserialize], chances are +//! you will be able to derive [SimpleStaticType] for it as well. This gives you access to +//! a dhall representation of your datatype that can be outputted to users, and +//! allows easy type-safe deserializing. +//! +//! ```edition2018 +//! use serde::Deserialize; +//! use dhall::SimpleStaticType; +//! +//! #[derive(Debug, Deserialize, SimpleStaticType)] +//! struct Point { +//! x: usize, +//! y: usize, +//! } +//! +//! fn main() { +//! // Some dhall data +//! // ./Point can be populated using Point::get_type().to_string() +//! let data = "{ x = 1, y = 1 + 1 } : ./Point"; +//! +//! // Convert the dhall string to a Point. +//! let point: Point = +//! dhall::from_str_auto_type(&data) +//! .expect("An error ocurred !"); +//! +//! // Prints "point = Point { x: 1, y: 2 }" +//! println!("point = {:?}", point); +//! } +//! ``` +//! +//! ### Loosely typed +//! +//! If you used to consume JSON or YAML in a loosely typed way, you can continue to do so +//! with dhall. You only need to replace [serde_json::from_str] or [serde_yaml::from_str] +//! with [dhall::from_str][from_str]. +//! More generally, if the [SimpleStaticType] derive doesn't suit your needs, you can still +//! deserialize any valid dhall file that serde can handle. +//! +//! [serde_json::from_str]: https://docs.serde.rs/serde_json/de/fn.from_str.html +//! [serde_yaml::from_str]: https://docs.serde.rs/serde_yaml/fn.from_str.html +//! +//! ```edition2018 +//! use std::collections::BTreeMap; +//! +//! let mut map = BTreeMap::new(); +//! map.insert("x".to_string(), 1); +//! map.insert("y".to_string(), 2); +//! +//! // Some dhall data +//! let data = "{ x = 1, y = 1 + 1 } : { x: Natural, y: Natural }"; +//! +//! // Deserialize it to a Rust type. +//! let deserialized_map: BTreeMap<String, usize> = +//! dhall::from_str(&data, None) +//! .expect("Failed reading the data !"); +//! assert_eq!(map, deserialized_map); +//! ``` +//! +//! You can of course specify a dhall type that the input should match. +//! +//! ```edition2018 +//! use std::collections::BTreeMap; +//! +//! let mut map = BTreeMap::new(); +//! map.insert("x".to_string(), 1); +//! map.insert("y".to_string(), 2); +//! +//! // Some dhall data +//! let point_data = "{ x = 1, y = 1 + 1 }"; +//! let point_type_data = "{ x: Natural, y: Natural }"; +//! +//! // Construct a type +//! let point_type = +//! dhall::from_str(point_type_data, None) +//! .expect("Could not parse the Point type"); +//! +//! // Deserialize it to a Rust type. +//! let deserialized_map: BTreeMap<String, usize> = +//! dhall::from_str(&point_data, Some(&point_type)) +//! .expect("Failed reading the data !"); +//! assert_eq!(map, deserialized_map); +//! ``` +//! +//! [dhall]: https://dhall-lang.org/ +//! [serde]: https://docs.serde.rs/serde/ +//! [serde::Deserialize]: https://docs.serde.rs/serde/trait.Deserialize.html + #[cfg(test)] #[macro_use] mod tests; |