Install a prebuilt version of `jupyterlab-ihaskell` automatically (#1270)

* ihaskell: automatically install the prebuilt labextension alongside the kernelspec

* README.md: Update to no longer mention installing jupyterlab-ihaskell

README.md

@@ -42,13 +42,6 @@ stack install --fast
 ihaskell install --stack
 ```
 
-If you want to use jupyterlab, you need to install the jupyterlab ihaskell
-extension to get syntax highlighting with:
-
-```bash
-jupyter labextension install jupyterlab-ihaskell
-```
-
 Run Jupyter.
 
 ```bash
@@ -203,13 +196,10 @@ Direct IHaskell to register itself as a Jupyter kernel.
 stack --docker exec ihaskell -- install --stack
 ```
 
-Optionally, install JupyterLab and the IHaskell JupyterLab extension for
-syntax highlighting. See the
-[`jupyterlab-ihaskell/README.md`](jupyterlab-ihaskell/README.md).
+Optionally, install JupyterLab.
 
 ```bash
 stack --docker exec pip3 -- install jupyterlab
-stack --docker exec bash -- -c 'cd jupyterlab-ihaskell;npm install;npm run build;jupyter labextension link .'
 ```
 
 Run the Jupyter notebook, with security disabled for testing, listening on all interfaces.

ihaskell.cabal

@@ -45,6 +45,9 @@ cabal-version:       1.16
 data-files:
     html/kernel.js
     html/logo-64x64.svg
+    jupyterlab-ihaskell/labextension/package.json
+    jupyterlab-ihaskell/labextension/static/*.js
+    jupyterlab-ihaskell/labextension/static/*.json
 
 library
   hs-source-dirs:      src

main/Main.hs

@@ -56,6 +56,7 @@ ihaskell (Args ConvertLhs args) = showingHelp ConvertLhs args $ convert args
 ihaskell (Args InstallKernelSpec args) = showingHelp InstallKernelSpec args $ do
   let kernelSpecOpts = parseKernelArgs args
   replaceIPythonKernelspec kernelSpecOpts
+  installLabextension
 ihaskell (Args (Kernel (Just filename)) args) = do
   let kernelSpecOpts = parseKernelArgs args
   runKernel kernelSpecOpts filename

release.nix

@@ -19,7 +19,7 @@ let
   ihaskellSourceFilter = src: name: type: let
     relPath = lib.removePrefix (toString src + "/") (toString name);
   in cleanSource name type && ( any (lib.flip lib.hasPrefix relPath) [
-    "src" "main" "html" "Setup.hs" "ihaskell.cabal" "LICENSE"
+    "src" "main" "html" "jupyterlab-ihaskell" "Setup.hs" "ihaskell.cabal" "LICENSE"
   ]);
   ihaskell-src         = filterSource (ihaskellSourceFilter ./.) ./.;
   ipython-kernel-src   = filterSource cleanSource ./ipython-kernel;

src/IHaskell/IPython.hs

@@ -11,6 +11,7 @@ module IHaskell.IPython (
     kernelName,
     KernelSpecOptions(..),
     defaultKernelSpecOptions,
+    installLabextension,
     ) where
 
 import           IHaskellPrelude
@@ -172,6 +173,30 @@ installKernelspec repl opts = void $ do
 
     SH.silently $ SH.run ipython cmd
 
+installLabextension :: IO ()
+installLabextension = SH.shelly $ do
+  -- Find the prebuilt extension directory
+  ihaskellDataDir <- liftIO $ Paths.getDataDir
+  let labextensionDataDir = ihaskellDataDir
+        SH.</> ("jupyterlab-ihaskell" :: SH.FilePath)
+        SH.</> ("labextension" :: SH.FilePath)
+
+  -- Find the $(jupyter --data-dir)/labextensions/jupyterlab-ihaskell directory
+  jupyter <- locateIPython
+  jupyterDataDir <- SH.silently $ SH.fromText . T.strip <$> SH.run jupyter ["--data-dir"]
+  let jupyterlabIHaskellDir = jupyterDataDir
+        SH.</> ("labextensions" :: SH.FilePath)
+        SH.</> ("jupyterlab-ihaskell" :: SH.FilePath)
+
+  -- Remove the extension directory with extreme prejudice if it already exists
+  SH.rm_rf jupyterlabIHaskellDir
+  -- Create an empty 'jupyterlab-ihaskell' directory to install our extension in
+  SH.mkdir_p jupyterlabIHaskellDir
+  -- Copy the prebuilt extension files over
+  extensionContents <- SH.ls labextensionDataDir
+  forM_ extensionContents $ \entry ->
+    SH.cp_r entry jupyterlabIHaskellDir
+
 -- | Replace "~" with $HOME if $HOME is defined. Otherwise, do nothing.
 subHome :: String -> IO String
 subHome path = SH.shelly $ do