1# jrsonnet2345## What is it67[Jsonnet](https://jsonnet.org/) is a data templating language89This Rust crate implements both jsonnet library and an alternative `jsonnet` executable based on it. For more information see [bindings](#Bindings).1011## Why?1213There already are multiple implementations of this standard implemented in different languages: [C++](https://github.com/google/jsonnet), [Go](https://github.com/google/go-jsonnet/), [Scala](https://github.com/databricks/sjsonnet).1415This implementation shows performance better than all existing implementations. For more information see [benchmarks](#Benchmarks).1617In the end, it's always fun to implement something in Rust.1819## Compliance with the [specification](https://jsonnet.org/ref/spec.html)2021- Passes all the original `examples` tests2223- Passes all the original `test_suite` tests except for those which require stacktraces identical to the default implementation (while also being available, vanilla-like stacktraces are not 100% identical):2425 ```jsonnet26 ## Explaining format27 ```28 RuntimeError("3")29 --> /home/lach/jsonnet-rs/a.jsonnet:1:2530 |31 1 | local a = "%0 10.20d" % error "3";32 | ^^^^^^^^^ error statement33 |34 --> /home/lach/jsonnet-rs/a.jsonnet:1:1135 |36 1 | local a = "%0 10.20d" % error "3";37 | ^^^^^^^^^^^^^^^^^^^^^^^ function <mod> call38 |39 --> /home/lach/jsonnet-rs/a.jsonnet:6:640 |41 6 | a: a,42 | ^ variable <a>43 |44 --> /home/lach/jsonnet-rs/a.jsonnet:3:645 |46 3 | b: self.a,47 | ^^^^^^ field access48 |49 --> /home/lach/jsonnet-rs/a.jsonnet:9:150 |51 9 | e.b52 | ^^^ field access53 |54 ```5556 ## Compact format (default)57 ```58 RuntimeError("3")59 /home/lach/jsonnet-rs/a.jsonnet:1:25-35: error statement60 /home/lach/jsonnet-rs/a.jsonnet:6:6-8 : variable <a>61 /home/lach/jsonnet-rs/a.jsonnet:3:6-13 : field access62 /home/lach/jsonnet-rs/a.jsonnet:9:1-5 : field access63 ```6465 ## Vanilla format66 ```67 RUNTIME ERROR: 368 a.jsonnet:1:25-34 thunk <a> from <$>69 <std>:237:21-22 thunk from <function <anonymous>>70 <std>:754:20-24 thunk from <function <anonymous>>71 <std>:32:25-26 thunk from <function <anonymous>>72 <std>:32:16-27 function <anonymous>73 <std>:754:8-25 function <anonymous>74 <std>:237:7-23 function <anonymous>7576 a.jsonnet:6:6-7 object <d>77 a.jsonnet:3:6-12 object <c>78 a.jsonnet:9:1-4 $79 During evaluation80 ```81 ```8283## Bindings8485Jrsonnet provides a standard `libjsonnet.so` shared library and should work as drop-in replacement for it8687WASM bingings are also available, Java bindings (Both JNI and WASM compiled to .class) are in progress8889See [bindings](./bindings/) for more information.9091## Benchmarks9293This is the fastest implementation of jsonnet both according to official benchmarks and real-life cluster configuration templating speed.9495Official benchmark results are available [in this gist](https://gist.github.com/CertainLach/5770d7ad4836066f8e0bd91e823e451b) which may get updated sometimes. It shows tests against Golang, C++ and Scala implementations showing the best performance in all cases.9697You can generate this report via provided nix flake9899## TO-DO list100101- [ ] Create docker container for easier benchmarking and/or benchmark in CI102- [ ] Implement and utilize mutable strings, arrays and objects instead of COWing when possible