docs: developer intro

CONTRIBUTING.md

@@ -1,7 +1,9 @@
-# Contributing to New Mars
+# Contributing to Ares
+
+Below are guidelines for contributions to Ares. For information on building and hacking on ares, see [DEVELOPERS.md](DEVELOPERS.md).
 
 ## Style
-Hoon should generally follow the kernel style.
+Hoon should generally follow the [Hoon Style Guide](https://docs.urbit.org/language/hoon/guides/style).
 
 Rust code must pass `cargo fmt --check`.
 
@@ -19,3 +21,4 @@ Examples:
 ## PR reviews
 Don't merge without them, don't forget to do them for others.
 
+

DEVELOPERS.md

@@ -0,0 +1,45 @@
+# Developing Ares
+
+## Nix
+Ares uses a Nix developer shell to set up the environment for rust builds. Please [Install Nix](https://nixos.org/download#download-nix).
+With Nix installed, you can run
+
+```bash
+nix develop
+```
+
+in `rust/` or any subdirectory, and you will be dropped into a BASH shell with the build environment set up. This will provide proper versions of non-rust dependencies, as well as the rust environment.
+
+## Rust
+
+To build Ares, start a nix development shell as above. Within the shell, in the `rust/ares` directory, you can run:
+
+```bash
+cargo build
+```
+
+to build the Ares executable. This will place the built executable at `target/debug/ares` under the `rust/ares` directory.
+
+Ares is made to run as an urbit "serf", meaning it is intended to be invoked by a "king" which sends it commands and performs side-effects specified by its output. We use the vere king. Special instructions for building the vere king to invoke Ares are forthcoming.
+
+To watch rust and check for errors, run
+
+```bash
+cargo watch --clear
+```
+
+Until terminated with ctrl-c, this will rebuild Ares library on any change to the underlying source files and report any warnings and errors. It will *not* produce the executable. You must run the build command above to rebuild the executable.
+
+## Hoon
+
+The Nock analysis and lowering for Ares is written in Hoon, and lives at `hoon/codegen.` It is meant to be jammed and included in the Ares binary. (See [`src/load.rs`](rust/ares/src/load.rs) in the Rust sources for details.)
+
+If the hoon source has been synced to a desk, e.g. `sandbox`, on a fakezod, then the build generator can be invoked as:
+
+```
+.cg/jam +sandbox!cg-make
+```
+
+This will build the Hoon standard library and the Ares Nock analysis as a "trap" meant to be run by Ares. The jammed output can be found at `<fakezod-pier>/.urb/put/cg.jam`, and should be copied to the `rust/ares/bin` directory, from whence the rust build will include it in the executable.
+
+Instructions on testing the analysis in a fakezod are forthcoming.

README.md

@@ -2,4 +2,7 @@
 
 A redesigned Mars for the Urth/Mars Urbit runtime. Currently WIP.
 
-Read the [proposal](docs/proposal/proposal-nock-performance.md) and [hypotheses](docs/proposal/hypotheses.md) for an overview. Before branching or opening a PR please review the [contribution guidelines](CONTRIBUTING.md).
+Read the [proposal](docs/proposal/proposal-nock-performance.md) and [hypotheses](docs/proposal/hypotheses.md) for an overview. 
+
+If you want to hack on Ares, read the [developer guide](DEVELOPERS.md).
+Before branching or opening a PR please review the [contribution guidelines](CONTRIBUTING.md).