Initial bindings/examples for writing Nix functions in Rust

.github/workflows/ci.yml

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+name: "CI"
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  id-token: "write"
+  contents: "read"
+  pull-requests: "write"
+
+jobs:
+  ci:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: git checkout
+        uses: actions/checkout@v4
+
+      - name: Install Nix
+        uses: DeterminateSystems/determinate-nix-action@main
+
+      - name: Set up FlakeHub Cache
+        uses: DeterminateSystems/flakehub-cache-action@main
+
+      - name: Build and test
+        run: |
+          nix flake check --all-systems --eval-cores 0 -L

.gitignore

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+*.wasm
+result
+/target/
+*~
+/*/tests/*.out

.vscode/tasks.json

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+{
+	"version": "2.0.0",
+	"tasks": [
+		{
+			"type": "cargo",
+			"command": "build",
+			"args": [
+				"--release"
+			],
+			"options": {
+				"env": {
+					"CARGO_BUILD_TARGET": "wasm32-unknown-unknown"
+				}
+			},
+			"problemMatcher": [
+				"$rustc"
+			],
+			"group": {
+				"kind": "build",
+				"isDefault": true
+			},
+			"label": "rust: cargo build"
+		}
+	]
+}

Cargo.toml

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+[workspace]
+members = [
+    "nix-wasm-rust",
+    "nix-wasm-plugin-fib",
+    "nix-wasm-plugin-ini",
+    "nix-wasm-plugin-yaml",
+    "nix-wasm-plugin-mandelbrot",
+    "nix-wasm-plugin-test",
+    "nix-wasm-plugin-grep",
+]
+resolver = "2"
+
+[profile.release]
+lto = true
+opt-level = 'z'
+strip = true

README.md

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+# `nix-wasm-rust`
+
+This crate helps you to write functions in Rust that can be executed by Nix at evaluation time using `builtins.wasm`. This repository also contains a number of tests and demos.
+
+To try it out:
+
+```console
+# nix shell .#nix # to get a version of Nix that has `builtins.wasm`
+
+# nix build # to build the Wasm functions
+
+# ls -l ./result/
+-r--r--r-- 3 root root  17396 Jan  1  1970 nix_wasm_plugin_fib.wasm
+-r--r--r-- 3 root root  64292 Jan  1  1970 nix_wasm_plugin_ini.wasm
+-r--r--r-- 3 root root  33277 Jan  1  1970 nix_wasm_plugin_mandelbrot.wasm
+-r--r--r-- 3 root root  29635 Jan  1  1970 nix_wasm_plugin_test.wasm
+-r--r--r-- 3 root root 205035 Jan  1  1970 nix_wasm_plugin_yaml.wasm
+
+# nix eval --impure --expr 'builtins.wasm ./result/nix_wasm_plugin_fib.wasm "fib" 40'
+warning: '/nix/store/1c9yg0mv…-nix-wasm-rust-0.1.0/nix_wasm_plugin_fib.wasm' function 'fib': greetings from Wasm!
+165580141
+
+# nix eval --raw --impure --expr 'builtins.wasm ./result/nix_wasm_plugin_mandelbrot.wasm "mandelbrot" { width = 150; }'
+```