Attempt to pull the latest doc generation stuff from hylo

.github/workflows/doc-extraction.yml

@@ -2,7 +2,7 @@ name: Extract And Publish Documentation
 
 defaults:
   run:
-    shell: bash -eo pipefail {0}
+    shell: 'bash -eo pipefail {0}'
 
 on:
   push:
@@ -24,34 +24,48 @@ concurrency:
   cancel-in-progress: false
 
 jobs:
-  # Build job
   build:
     if: github.repository == 'hylo-lang/Lotsawa'
     runs-on: macos-latest
     steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-      - name: Make site Directory
-        run: mkdir -p _site/docc
-      - name: Prepare Shell Environment
-        # The format of the ${GITHUB_ENV} file is extremely restrictive; it apparently only supports
-        # lines of the form:
-        #
-        #   <variable-name>=<one-line-of-text>
-        #
-        # And a multiline version
-        # (https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#multiline-strings).
-        # It is not interpreted directly by a shell, so any quotes or other special characters are
-        # taken literally.
-
-        # FIXME: REF_URL_COMPONENT computation is probably wrong for some refs.
-        run: |
-          echo "REPO_SANS_OWNER=${GITHUB_REPOSITORY##*/}
-          REF_URL_COMPONENT=${GITHUB_REF##*/}
-          " >> "${GITHUB_ENV}"
+    - uses: actions/checkout@v4
+      with:
+        submodules: true
+        show-progress: false
+
+    - name: Make site Directory
+      run: mkdir -p _site/docc
+
+    - name: Install Jazzy
+      run: |
+        gem install jazzy
+
+    - name: Setup swift
+      uses: swift-actions/setup-swift@v1
+      with:
+        swift-version: 5.9
 
-      - name: Run DocC
+    - name: Prepare Shell Environment
+      # The format of the ${GITHUB_ENV} file is extremely restrictive; it apparently only supports
+      # lines of the form:
+      #
+      #   <variable-name>=<one-line-of-text>
+      #
+      # And a multiline version
+      # (https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#multiline-strings).
+      # It is not interpreted directly by a shell, so any quotes or other special characters are
+      # taken literally.
+
+      # FIXME: REF_URL_COMPONENT computation is probably wrong for some refs.
+      run: |
+        echo "REPO_SANS_OWNER=${GITHUB_REPOSITORY##*/}
+        REF_URL_COMPONENT=${GITHUB_REF##*/}
+        LOTSAWA_ENABLE_DOC_GENERATION=1
+        " >> "${GITHUB_ENV}"
+
+      - name: Extract with DocC
         run: |
+          mkdir -p _site/docc
           swift package --allow-writing-to-directory ./_site \
           generate-documentation \
           --product Lotsawa \
@@ -63,10 +77,10 @@ jobs:
           --source-service github \
           --source-service-base-url "https://github.com/${GITHUB_REPOSITORY}/blob/${REF_URL_COMPONENT}" \
           --checkout-path "$(pwd)"
-      - name: Install jazzy
-        run: gem install jazzy
-      - name: Run Jazzy
+
+      - name: Extract with Jazzy
         run: |
+          mkdir -p _site/jazzy
           jazzy \
           --source-host-files-url "https://github.com/${GITHUB_REPOSITORY}/blob/${REF_URL_COMPONENT}" \
           --module Lotsawa \

Package.swift

@@ -1,11 +1,20 @@
 // swift-tools-version: 5.7
 import PackageDescription
+import Foundation
 
 let CitronParser
   = Target.Dependency.product(name: "CitronParserModule", package: "citron")
 let CitronLexer
   = Target.Dependency.product(  name: "CitronLexerModule", package: "citron")
 
+/// Dependencies for documentation extraction.
+///
+/// Most people don't need to extract documentation; set `HYLO_ENABLE_DOC_GENERATION` in your
+/// environment if you do.
+let docGenerationDependency: [Package.Dependency] =
+  ProcessInfo.processInfo.environment["LOTSAWA_ENABLE_DOC_GENERATION"] != nil
+  ? [.package(url: "https://github.com/apple/swift-docc-plugin.git", from: "1.1.0")] : []
+
 let package = Package(
   name: "Lotsawa",
     platforms: [
@@ -20,7 +29,9 @@ let package = Package(
       .package(url: "https://github.com/dabrahams/citron.git", from: "2.1.1"),
       .package(url: "https://github.com/apple/swift-docc-plugin.git", from: "1.1.0"),
       .package(url: "https://github.com/SwiftPackageIndex/SPIManifest.git", from: "0.12.0")
-    ],
+    ]
+      + docGenerationDependency,
+
     targets: [
         .target(
             name: "Lotsawa",