From 2f2141328ca65c5f4e2f918ed61458057198ffba Mon Sep 17 00:00:00 2001
From: Roland Conybeare <rconybeare@gmail.com>
Date: Sat, 10 May 2025 12:15:55 -0500
Subject: [PATCH] + README

---
 README.md | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 README.md

diff --git a/README.md b/README.md
new file mode 100644
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+++ b/README.md
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+# Introduction
+
+Local nix build for xo libraries.
+Intended for local development work, with source in immediate subdirectories.
+
+## Features
+
+- native c++
+- deterministic simulation
+- reflection
+- python bindings
+
+## Getting Started
+
+### Cmake build
+
+If `nix` is available, you probably prefer the nix build.
+Otherwise continue reading..
+
+The cmake build has two phases, because it needs to bootstrap
+generated `xo-cmake-config`, `xo-build` helpers.
+
+```
+$ cd xo
+$ PREFIX=/path/to/say/usr/local
+# phase 1
+$ cmake -B .build0 -S xo-cmake -DCMAKE_INSTALL_PREFIX=${PREFIX}
+$ cmake --build .build0
+$ cmake --install .build0
+# phase 2
+$ cmake -B .build -S . -DCMAKE_INSTALL_PREFIX=${PREFIX}
+$ cmake --build .build
+$ cmake --install .build
+```
+
+### Nix Build
+
+Nix build uses toplevel `default.nix`,
+along with top-level `pkgs/xo-foo.nix` for each subproject `foo`.
+It doesn't interact with toplevel `CMakeLists.txt`.
+
+```
+$ nix-build -A xo-userenv
+```