Migrate CLI implementation to Rust

.dockerignore

@@ -6,11 +6,9 @@
 .vscode
 
 # Local build artifacts
+target/
 why
 why.exe
-tests/test_why_core
-tests/test_why_core.exe
-nimcache/
 
 # Editor/OS noise
 Thumbs.db

.github/scripts/generate_formula.sh

@@ -6,44 +6,13 @@ VERSION=$1
 URL=$2
 SHA256=$3
 
-NIMBLE_FILE="why_cli.nimble"
+readonly VERSION URL SHA256
 
-if [ ! -f "$NIMBLE_FILE" ]; then
-    echo "Error: $NIMBLE_FILE not found." >&2
+if [ ! -f "Cargo.toml" ]; then
+    echo "Error: Cargo.toml not found." >&2
     exit 1
 fi
 
-get_nimble_version() {
-    local pkg_name=$1
-    # Extract version from lines like: requires "cligen >= 1.7.0"
-    grep "requires \"$pkg_name" "$NIMBLE_FILE" | sed -E 's/.*>= *([0-9.]+).*/\1/'
-}
-
-generate_resource() {
-    local name=$1
-    local repo_url_base=$2
-
-    local ver=$(get_nimble_version "$name")
-
-    if [ -z "$ver" ]; then
-        echo "Error: Could not find version for $name in $NIMBLE_FILE" >&2
-        exit 1
-    fi
-
-    local dl_url="${repo_url_base}/archive/refs/tags/${ver}.tar.gz"
-
-    local tmp_file="/tmp/${name}-${ver}.tar.gz"
-
-    curl -sL "$dl_url" -o "$tmp_file"
-    local sha=$(sha256sum "$tmp_file" | awk '{print $1}')
-    rm "$tmp_file"
-
-    echo "  resource \"$name\" do"
-    echo "    url \"$dl_url\""
-    echo "    sha256 \"$sha\""
-    echo "  end"
-}
-
 cat <<EOF
 class Why < Formula
   desc "Show where a command on your system really comes from"
@@ -52,22 +21,10 @@ class Why < Formula
   sha256 "${SHA256}"
   license "MIT"
 
-  depends_on "nim" => :build
-
-EOF
-
-# Define dependencies here. The version is auto-detected from .nimble.
-generate_resource "cligen" "https://github.com/c-blake/cligen"
-
-cat <<EOF
+  depends_on "rust" => :build
 
   def install
-    resource("cligen").stage do
-      (buildpath/"vendor/cligen").install Dir["*"]
-    end
-
-    system "nim", "c", "-d:release", "--path:#{buildpath}/vendor/cligen", "-o:why", "src/why.nim"
-    bin.install "why"
+    system "cargo", "install", "--locked", *std_cargo_args
   end
 
   test do

.github/workflows/ci.yml

@@ -20,36 +20,49 @@ jobs:
           - ubuntu-latest
           - macos-latest
     steps:
-      - uses: actions/checkout@v4
-
-      - name: Install Nim
-        uses: jiro4989/setup-nim-action@v2
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
-          nim-version: '2.2.6'
+          persist-credentials: false
 
-      - name: Cache Nimble and Nim
-        uses: actions/cache@v4
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
         with:
-          path: |
-            ~/.nimble
-            ~/.cache/nim
-          key: ${{ runner.os }}-nim-2.2.6-nimble-${{ hashFiles('nimble.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-nim-2.2.6-nimble-
+          components: clippy, rustfmt
+
+      - name: Cache Cargo
+        uses: Swatinem/rust-cache@42dc69e1aa15d09112580998cf2ef0119e2e91ae # v2
+
+      - name: Check Formatting
+        run: cargo fmt --check
 
-      - name: Install Dependencies
-        run: nimble install -y --depsOnly
+      - name: Run Clippy
+        run: cargo clippy --all-targets -- -D warnings
 
       - name: Run Tests
-        run: nimble test
+        run: cargo test --locked
 
   e2e:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
 
       - name: Run E2E Tests
         run: ./tests/e2e/run.sh
         env:
           E2E_JOBS: 2
+
+  nix:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@b97f05dcb019ddea06450a50ef6203d2fdc19fee # v31
+
+      - name: Build Nix Package
+        run: nix build

.github/workflows/release.yml

@@ -16,42 +16,48 @@ jobs:
       matrix:
         include:
           - os: ubuntu-24.04
+            target: x86_64-unknown-linux-gnu
             target_os: linux
             cpu: amd64
             archive_name: why-linux-amd64
-          - os: ubuntu-24.04
+            install_cross: ''
+            linker_env: ''
+          - os: ubuntu-24.04-arm
+            target: aarch64-unknown-linux-gnu
             target_os: linux
             cpu: arm64
             archive_name: why-linux-arm64
-            install_cross: sudo apt-get update && sudo apt-get install -y gcc-aarch64-linux-gnu
-            nim_flags: --cpu:arm64 --os:linux --gcc.exe:aarch64-linux-gnu-gcc --gcc.linkerexe:aarch64-linux-gnu-gcc
+            install_cross: ''
+            linker_env: ''
           - os: macos-15-intel
+            target: x86_64-apple-darwin
             target_os: darwin
             cpu: amd64
             archive_name: why-darwin-amd64
+            install_cross: ''
+            linker_env: ''
           - os: macos-15
+            target: aarch64-apple-darwin
             target_os: darwin
             cpu: arm64
             archive_name: why-darwin-arm64
+            install_cross: ''
+            linker_env: ''
 
     steps:
-      - uses: actions/checkout@v6
-
-      - name: Cache Nimble dependencies
-        uses: actions/cache@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
-          path: ~/.nimble
-          key: ${{ runner.os }}-nimble-${{ hashFiles('nimble.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-nimble-
+          persist-credentials: false
 
-      - name: Install Nim
-        uses: jiro4989/setup-nim-action@v2
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
         with:
-          nim-version: '2.2.6'
+          targets: ${{ matrix.target }}
 
-      - name: Install Dependencies
-        run: nimble install -y --depsOnly
+      - name: Cache Cargo
+        uses: Swatinem/rust-cache@42dc69e1aa15d09112580998cf2ef0119e2e91ae # v2
+        with:
+          save-if: "false"
 
       - name: Install Cross-compiler (Linux ARM64 only)
         if: matrix.install_cross != ''
@@ -60,14 +66,14 @@ jobs:
       - name: Build
         shell: bash
         run: |
-          nimble build -d:release ${{ matrix.nim_flags }}
-          mv why ${{ matrix.archive_name }}
+          ${{ matrix.linker_env }} cargo build --release --locked --target ${{ matrix.target }}
+          cp target/${{ matrix.target }}/release/why ${{ matrix.archive_name }}
 
       - name: Create Archive
         run: tar czf ${{ matrix.archive_name }}.tar.gz ${{ matrix.archive_name }}
 
       - name: Release to GitHub
-        uses: softprops/action-gh-release@v1
+        uses: softprops/action-gh-release@3bb12739c298aeb8a4eeaf626c5b8d85266b0e65 # v2
         if: startsWith(github.ref, 'refs/tags/')
         with:
           files: ${{ matrix.archive_name }}.tar.gz
@@ -80,13 +86,16 @@ jobs:
     if: startsWith(github.ref, 'refs/tags/') && !contains(github.ref, '-')
     steps:
       - name: Checkout why-cli repository (for scripts)
-        uses: actions/checkout@v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+        with:
+          persist-credentials: false
 
       - name: Checkout tap repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
         with:
           repository: akriaueno/homebrew-tap
           token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }}
+          persist-credentials: false
           path: homebrew-tap
 
       - name: Ensure Formula directory exists
@@ -105,8 +114,8 @@ jobs:
           # Calculate SHA256 hash
           SHA256=$(sha256sum source.tar.gz | awk '{print $1}')
 
-          echo "sha=$SHA256" >> $GITHUB_OUTPUT
-          echo "url=$SOURCE_URL" >> $GITHUB_OUTPUT
+          echo "sha=$SHA256" >> "$GITHUB_OUTPUT"
+          echo "url=$SOURCE_URL" >> "$GITHUB_OUTPUT"
 
       - name: Generate Formula
         run: |
@@ -123,7 +132,7 @@ jobs:
           echo "========================="
 
       - name: Create PR on tap repository
-        uses: peter-evans/create-pull-request@v8
+        uses: peter-evans/create-pull-request@5f6978faf089d4d20b00c7766989d076bb2fc7f1 # v8
         with:
           token: ${{ secrets.GH_PERSONAL_ACCESS_TOKEN }} # fine-grained PAT (homebrew-tap, contents:write & pull-requests:write)
           path: homebrew-tap

.gitignore

@@ -1,16 +1,10 @@
 # Output binaries
+/target/
+result
 why
 why.exe
-tests/test_why_core
-tests/test_why_core.exe
 tests/e2e/why-linux-amd64
 
-# Nimble files
-nimble.develop
-config.nims
-nimble.paths
-nimbledeps
-
 # LLM utilities
 repomix-output.xml