The example should probably switch to psc and make psa optional, or make external dependencies more clear

Currently, if there is no purescript-psa installed, then the example fails with a very ambiguous error:

events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: spawn psaa ENOENT
    at exports._errnoException (util.js:1026:11)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:193:32)
    at onErrorNT (internal/child_process.js:359:16)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickCallback (internal/process/next_tick.js:98:9)

This is going to be very discouraging for anybody who wants to quickly try purs-loader and purescript with webpack. On purs-loader page, it mentions quickly that it uses purescript-psa, but I think it's a good idea to make the example repository as fail-safe as possible and mention it loudly here as well.

My suggestion is to list every external dependency clearly upfront in the README.md. If I'm not missing anything, this consists of purescript-psa (psa) and purescript (psc), nodejs (node), webpack (webpack). I have specified their CLI names in brackets to that it's easier to verify whether each one exists by running --version on each of them. I can create a PL later.

I think it is a great idea to be explicit about all of the dependencies. Putting this in the README would be a welcome addition. In terms of not having psa installed, shouldn't it be installed when the user runs npm install? I just want to make sure I understand how to reproduce the issue you had. Thanks!

No it's not installed. In my understanding, npm install does not install packages globally. You would need npm install -g purescript-psa for that. I'm on Nix, where it wouldn't allow npm command to install anything globally to begin with and since npm install runs without errors this means it alters only local packages, the ones that don't get added to $PATH.

I would try npm uninstall -g purescript-psa and then npm install again to test whether there was purescript-psa installed globally and to reproduce the issue.

Right, the npm install would not install anything globally. But it should install psa locally in node_modules/.bin, and this is what the purs-loader expects. It should take the binaries in node_modules/.bin first when running webpack through npm. In the README it suggests npm start or npm run webpack:server. I believe this should pick up the local install of psa. Let me know if this works for you.

You're right npm run webpack:server works without global purescript-psa. npm start, on the other hand, outputs:

> npm run
Lifecycle scripts included in purescript-webpack-example:
  start
    node bundle.js

available via `npm run-script`:
  webpack
    DEBUG=purs-loader webpack --progress --bail
  webpack:watch
    webpack --progress --watch
  webpack:server
    webpack-dev-server --progress --inline --hot
  webpack:server:debug
    DEBUG=purs-loader webpack-dev-server --progress --inline --hot
  psc
    psc 'bower_components/purescript-*/src/**/*.purs' 'src/**/*.purs'
  psc-bundle
    psc-bundle output/**/*.js

Glad it works! Note that for npm start, all steps are required as mentioned in the readme.

bower install

npm install

npm run webpack

npm start

Yeah, for npm start it's probably because npm run webpack failed and I tried doing it the other way. It failed like this:

>>> npm run webpack
> purescript-webpack-example@0.1.0 webpack /tmp/purescript-webpack-example
> DEBUG=purs-loader webpack --progress --bail
                                                                                                                                                                                  10% 0/1 build modules  purs-loader loader called Example +0ms
  purs-loader spawning compiler psa [ '--output=output', 'bower_components/purescript-*/src/**/*.purs', 'src/**/*.purs' ] +2ms
  purs-loader compiling PureScript... +4ms
  purs-loader finished compiling PureScript. +309ms
ModuleBuildError: Module build failed: Error: compilation failed
    at ChildProcess.<anonymous> (/tmp/purescript-webpack-example/node_modules/purs-loader/lib/Psc.js:48:16)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:191:7)
    at maybeClose (internal/child_process.js:877:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)
    at DependenciesBlock.onModuleBuildFailed (/tmp/purescript-webpack-example/node_modules/webpack-core/lib/NormalModuleMixin.js:315:19)
    at nextLoader (/tmp/purescript-webpack-example/node_modules/webpack-core/lib/NormalModuleMixin.js:270:31)
    at /tmp/purescript-webpack-example/node_modules/webpack-core/lib/NormalModuleMixin.js:292:15
    at context.callback (/tmp/purescript-webpack-example/node_modules/webpack-core/lib/NormalModuleMixin.js:148:14)
    at Object.reject (/tmp/purescript-webpack-example/node_modules/purs-loader/lib/index.js:116:14)
    at /tmp/purescript-webpack-example/node_modules/purs-loader/lib/index.js:165:25
    at tryCatcher (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/promise.js:510:31)
    at Promise._settlePromise (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/promise.js:567:18)
    at Promise._settlePromise0 (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/promise.js:612:10)
    at Promise._settlePromises (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/promise.js:687:18)
    at Async._drainQueue (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/async.js:133:16)
    at Async._drainQueues (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/async.js:143:10)
    at Immediate.Async.drainQueues (/tmp/purescript-webpack-example/node_modules/bluebird/js/release/async.js:17:14)
    at runCallback (timers.js:637:20)
    at tryOnImmediate (timers.js:610:5)
    at processImmediate [as _immediateCallback] (timers.js:582:5)

npm ERR! Linux 4.4.35
npm ERR! argv "/nix/store/9ps69qzr5x9szkdk81gviyr9mck51nzn-nodejs-6.9.1/bin/node" "/home/jon/.nix-profile/bin/npm" "run" "webpack"
npm ERR! node v6.9.1
npm ERR! npm  v3.10.8
npm ERR! code ELIFECYCLE
npm ERR! purescript-webpack-example@0.1.0 webpack: `DEBUG=purs-loader webpack --progress --bail`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the purescript-webpack-example@0.1.0 webpack script 'DEBUG=purs-loader webpack --progress --bail'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the purescript-webpack-example package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR!     DEBUG=purs-loader webpack --progress --bail
npm ERR! You can get information on how to open an issue for this project with:
npm ERR!     npm bugs purescript-webpack-example
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!     npm owner ls purescript-webpack-example
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR!     /tmp/purescript-webpack-example/npm-debug.log

Anyway, there is something strange going on because it occasionally fails and occasionally not, even with npm run webpack:server. By occasionally, I mean if you use it for a while and run npm install, etc, not between individual runs. I found that the most reliable way is by running webpack and webpack --watch and having everything globally (purescript-psa and webpack), at least it's this way on Nix.

>>> npm run webpack:server

> purescript-webpack-example@0.1.0 webpack:server /tmp/purescript-webpack-example
> webpack-dev-server --progress --inline --hot
                                                                              70% 1/1 build modules http://localhost:4008/
webpack result is served from /
content is served from .                                                                           
ERROR in ./src/Example.purs
Module build failed: Error: compilation failed
    at ChildProcess.<anonymous> (/tmp/purescript-webpack-example/node_modules/purs-loader/lib/Psc.js:48:16)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:191:7)
    at maybeClose (internal/child_process.js:877:16)
    at Socket.<anonymous> (internal/child_process.js:334:11)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at Pipe._handle.close [as _onclose] (net.js:498:12)
 @ multi main

ERROR in events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: spawn /tmp/purescript-webpack-example/node_modules/purescript/vendor/psc ENOENT
    at exports._errnoException (util.js:1026:11)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:193:32)
    at onErrorNT (internal/child_process.js:359:16)
    at _combinedTickCallback (internal/process/next_tick.js:74:11)
    at process._tickCallback (internal/process/next_tick.js:98:9)
    at Module.runMain (module.js:606:11)
    at run (bootstrap_node.js:394:7)
    at startup (bootstrap_node.js:149:9)
    at bootstrap_node.js:509:3

Thanks for reporting this. I haven't tried it on Nix. I am not quite sure what is going on. Do you think it is related to the purs-loader or how npm is installing dependencies?

purs-loader works perfectly with webpack and webpack --watch.

I think I figured out what was causing this. This appears to be Nix related. Basically, npm puts the binary in /tmp/purescript-webpack-example/node_modules/purescript/vendor/psc, then something tries to spawn the process, after all, it obviously needs psc compiler to compile. However, that binary dynamically links /lib64/ld-linux-x86-64.so.2 that does not exist on this system:

> cd /tmp/purescript-webpack-example/node_modules/purescript/vendor/
> file ./psc
./psc: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.24, BuildID[sha1]=d699fdefc2052263c93221500933c7431782f73a, stripped

Normally, Nix would patch it and provide another path to the library as seen here, when psc is installed through Nix:

> pwd
/nix/store/ilmpr6p1yga5sk3sqg5xhqwsbn301n7k-purescript-0.10.7/bin
> file ./psc
./psc: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /nix/store/amjgskg17wv125v9kahqdfxh8sx6mxgp-glibc-2.24/lib/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, stripped

In npm's case, if you even call ./psc from shell, it will output that file or directory does not exist. Not because the binary itself does not exist there, but because it links something that does not exist. It's very confusing and Linux should provide a clearer error in this case, IMO. When spawn called, it gets the same error that file does not exists and outputs the error as if psc does not exist there, which is not true.

So, when you run webpack that's installed globally it looks at $PATH for compiler and finds the one that is linked properly. When you run npm run it finds compiler that npm provided and fails.

Great! Glad that you got this working. Do you think we should say anything about this in the troubleshooting section in the purs-loader README?

Yeah, probably. I think Nix usage among Purescript crowd will be higher than other JS transpilers, based on similarities in philosophy.

Would you be willing to write up a short description of how you fixed this?

…

On Sat, Feb 25, 2017 at 10:55 cyrbon ***@***.***> wrote: Yeah, probably. I think Nix usage among Purescript crowd will be higher than other JS transpilers, based on similarities in philosophy. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#5 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAVYy0ofEA9OI1NE4rbJI-d88yP0-_xnks5rgE7qgaJpZM4MMBt4> .

Of course. I'll create a pull request soon.

Thanks!

…

On Sat, Feb 25, 2017 at 10:58 cyrbon ***@***.***> wrote: Of course. I'll create a pull request soon. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#5 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAVYyxzhiN00VDepY_MgUZr2jsmOQDN0ks5rgE-UgaJpZM4MMBt4> .

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The example should probably switch to `psc` and make `psa` optional, or make external dependencies more clear #5

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The example should probably switch to psc and make psa optional, or make external dependencies more clear #5

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ethul commented on Feb 25, 2017

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cyrbon commented on Feb 25, 2017

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The example should probably switch to `psc` and make `psa` optional, or make external dependencies more clear #5