Add Reason asset type #342

rrdelaney · 2017-12-19T04:32:57Z

This adds the Reason asset type to .re files.

Right now this is pretty basic and only loads the recommended Reason configuration. I can update it to use other configurations if you want, but overall I think this is a good starting point.

The code for this is pretty simple -- a lot of the work was already done in the Reason commuity's wrapper for the build tool, bsb-js. That should handle requiring the build tool per-project and error handling already, so little logic other than "run the build" and "read the result" are needed.

davidnagli · 2017-12-19T04:41:40Z

Nice!

brandon93s · 2017-12-19T04:46:35Z

src/Parser.js

@@ -12,6 +12,7 @@ class Parser {
    this.registerExtension('es6', './assets/JSAsset');
    this.registerExtension('jsm', './assets/JSAsset');
    this.registerExtension('mjs', './assets/JSAsset');
+    this.registerExtension('re', './assets/ReasonAsset');


What about .ml files?

Added for OCaml files too 😄

brandon93s · 2017-12-19T04:47:46Z

src/assets/ReasonAsset.js

+const fs = require('fs');
+const JSAsset = require('./JSAsset');
+const config = require('../utils/config');
+const localRequire = require('../utils/localRequire');


Appear to be unused:

const config = require('../utils/config'); const localRequire = require('../utils/localRequire');

Yep, they were. Thanks!

brandon93s · 2017-12-19T04:49:08Z

src/assets/ReasonAsset.js

+    // the Reason compilation process.
+    await bsb.runBuild();
+
+    this.contents = await new Promise((resolve, reject) => {


Could use ../utils/promisify on fs.readFile instead of new Promise.

brandon93s · 2017-12-19T04:51:45Z

See parcel-plugin-bucklescript (npm) for an existing plugin. Similar implementation, but may provide a bit more on the config front.

davidnagli · 2017-12-19T04:54:05Z

I just tried it out and I’m consistently getting the error:

🚨  script: bsb: No such file or directory

And yes, I do have a file called hello.re:

> ls
    dist     hello.re

Full output:

> parcelfork hello.re
    ⏳  Building...
    Server running at http://localhost:1234
    🚨  script: bsb: No such file or directory

^C

parcelfork is just a little alias I set up to run the version of Parcel that I have forked locally (in this case switched to your PR HEAD). It’s essentially just calling bin/cli.js

If you’re reproducing this, here’s the exact code I use (taken from here):

hello.re

type tree = Leaf | Node(int, tree, tree);

let rec sum =
  fun
  | Leaf => 0
  | Node(value, left, right) => value + sum(left) + sum(right);

let myTree =
  Node(
    1,
    Node(2, Node(4, Leaf, Leaf), Node(6, Leaf, Leaf)),
    Node(3, Node(5, Leaf, Leaf), Node(7, Leaf, Leaf))
  );

sum(myTree) |> Js.log;

rrdelaney · 2017-12-19T05:03:30Z

@brandon93s Thanks for the link! It looks like the implementation they used adapted from bs-loader, a Webpack loader I wrote for BuckleScript. bs-loader has a few problems and complexities, so we're actively trying to move away from it. By only supporting a small set of BuckleScript configurations the code can be simpler, faster, and more predictable.

@davidnagli You'll need to run the following commands in your project to get set up with Reason:

$ npm install --dev bs-platform
$ touch bsconfig.json
$ touch src/index.re

and then copy this into bsconfig.json:

{
  "name": "reason-parcel-example",
  "sources": [
    "src"
  ],
  "refmt": 3,
  "package-specs": {
    "module": "commonjs",
    "in-source": true
  },
  "suffix": ".bs.js"
}

rrdelaney · 2017-12-19T05:41:11Z

Uhh, I don't think that last one should have failed. The HTML test failed for some reason?

devongovett · 2017-12-19T08:17:00Z

src/assets/ReasonAsset.js

+    // This is a simplified use-case for Reason - it only loads the recommended
+    // BuckleScript configuration to simplify the file processing.
+    const outputFile = this.name.replace(/\.(re|ml)$/, '.bs.js');
+    const outputContent = await readFile(outputFile);


is there no way to do this without writing to a temporary file first?

Sorry, what do you mean by writing to a temp file?

I mean, it seems like bsb-js or whatever that uses is writing its output to a temp file, which we then need to read here. Is there a way to avoid that?

e.g. the compileFile function as used by parcel-plugin-bucklescript seems to return the output directly to a variable

compileFile basically does the same thing here — reading the result of the output. Currently BuckleScript has no way of compiling Reason like that without seriously compromised performance and maintainability.

devongovett · 2017-12-19T08:18:37Z

package.json

@@ -14,6 +14,7 @@
    "babylon": "^6.17.4",
    "babylon-walk": "^1.0.2",
    "browser-resolve": "^1.11.2",
+    "bsb-js": "^1.0.1",


Let's not take this on as a dependency - people can install it locally in their projects. can you move it to a dev dep for the tests and use localRequire below?

bsb-js is a thin wrapper over finding and running a BuckleScript executable, kind of like the logic in the TS asset. I developed he package for use cases like this, adding Reason support easily to a new bundler.

This doesn’t actually depend on BuckleScript, so users would still have to install that themselves. Requiring users to install it themselves wouldn’t make that much sense because it’s a package meant to be used by tooling.

With this being the case, it is ok to add it as a dependency? If it helps at all, I’m the maintainer of that package.

After #306 lands this won't be such a big deal since deps like this will be automatically installed by parcel as needed.

Even so, bsb-js is still a pretty small dependency to add. It doesn't include the entire compiler toolchain and has no dependencies itself. The package should only add ~2.7k

It's a slippery slope I think. We don't do it for other asset types, so I don't want to start now.

devongovett · 2017-12-19T08:18:57Z

src/assets/ReasonAsset.js

+    // Other Asset types use `localRequire` but the `bsb-js` package already
+    // does that internally. This should also take care of error handling in
+    // the Reason compilation process.
+    if (process.env.NODE_ENV !== 'test') {


why not building in the tests?

Building during test would require adding BuckleScript as a dev dependency. BS is a big native binary that compiles itself on install, which takes about 7 minutes.

The wrapper around BuckleScript, bsb-js, is pretty well tested, so the tests for Reason only test the file-loading logic.

devongovett · 2017-12-19T08:19:31Z

test/integration/reason/local.bs.js

@@ -0,0 +1,11 @@
+// Generated by BUCKLESCRIPT VERSION 1.9.2, PLEASE EDIT WITH CARE


doesn't seem like this should be committed...

I hard coded the result of compiling the Reason file with BuckleScript so that we don’t have to run it when running the tests. BuckleScript is a binary that compiles itself during installation which could take a while. By hard coding the result we can test just the loading logic, because the logic to run BuckleScript is contained in another package, bsb-js.

brandon93s · 2017-12-19T13:18:08Z

@rrdelaney - That test experiences random failures; a fix for it is now in master.

_{Sent with GitHawk}

…o reason

rrdelaney · 2017-12-20T07:21:53Z

@brandon93s Thanks 😄 I just pulled from upstream

devongovett · 2017-12-21T19:41:37Z

I moved bsb-js to a dev dependency and used localRequire. That should get it autoinstalled when used once #306 lands.

* Add bsb-js dependency * Add ReasonAsset type * Actually add the Reason asset type * Add OCaml file type, add integration test, remote unused imports * use promisify for reading files * Fix integration tests

rrdelaney added 3 commits December 18, 2017 19:53

Add bsb-js dependency

7cb5164

Add ReasonAsset type

e864f7c

Actually add the Reason asset type

565b89a

brandon93s reviewed Dec 19, 2017

View reviewed changes

Add OCaml file type, add integration test, remote unused imports

56cd8ef

rrdelaney added 2 commits December 18, 2017 21:09

use promisify for reading files

66e24fa

Fix integration tests

3fcd205

devongovett requested changes Dec 19, 2017

View reviewed changes

Merge branch 'master' of https://github.com/parcel-bundler/parcel int…

51d65ba

…o reason

devongovett approved these changes Dec 21, 2017

View reviewed changes

devongovett merged commit 47e9192 into parcel-bundler:master Dec 21, 2017

abdullahtariq1171 mentioned this pull request Aug 19, 2019

add @parcel/transformer-reason #3417

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Add Reason asset type #342

Add Reason asset type #342

rrdelaney commented Dec 19, 2017

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devongovett commented Dec 21, 2017

		@@ -0,0 +1,11 @@
		// Generated by BUCKLESCRIPT VERSION 1.9.2, PLEASE EDIT WITH CARE

Add Reason asset type #342

Add Reason asset type #342

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rrdelaney commented Dec 19, 2017

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brandon93s commented Dec 19, 2017

rrdelaney commented Dec 20, 2017

devongovett commented Dec 21, 2017