ReasonProject

Installation of Reason project and development environments via npm.

Requirements: npm (currently tested on Mac, Linux, and Windows Linux subsystem).

ReasonProject installs the Reason toolchain into a local directory using npm. ReasonProject can therefore be used as a template for new projects, but can also be used to install the toolchain into the global environment. ReasonProject includes: the compiler toolchain, the source formatter, REPL, and IDE support for popular editors.

A sandboxed environment models dependencies and builds them into a local directory so that it works reliably for anyone. Installing tools into your global environment is simply a matter of sourcing the sandboxed environment in your .bashrc. It's easy to make sandboxed local environments global, and very hard to do the reverse, so ReasonProject starts with local environments.

Install

Install by cloning the repo and running npm install. This installs all dependencies locally into the ReasonProject directory.

git clone https://github.com/reasonml/ReasonProject.git
cd ReasonProject
npm install

Project Commands

Once built, ReasonProject generates an environment that you can temporarily load when executing commands. The environment contains an enhanced PATH containing binaries built by your dependencies, but this environment isn't loaded into your global path. Some npm run commands have been setup to allow you to run some basic tasks, as well as any custom command, all within the project environment.

Run, Change, Rebuild

There are a couple of built in commands declared in package.json that you can execute via npm run. For example: "npm run start", "npm run reasonBuild" and "npm run clean". You can also add your own named scripts which give you a nicer alias like npm run myScriptName.

npm run reasonBuild  # Rebuilds after changing
npm run start        # Runs the compiled app
npm run clean        # Clean if you need to!

A single test file ./src/Test.re is included. Make a simple change to it and then run the commands above to see it effect the output.

REPL

The rtop REPL is built into the sandbox. The command npm run top starts the REPL.

# Opens `rtop` from the sandbox.
npm run top

Custom Commands

To do anything beyond those basic, preconfigured commands, you just prefix your command with npm run env --. You should pass the actual command you want to run after --.

# By default nothing is found!
which refmt

 > Not Found!

# Prefix with "npm run env --" and it finds it!
npm run env -- which refmt

 > ~/ReasonProject/node_modules/reason/_build/ocamlfind/bin/refmt

If this becomes tedious, you can add your own named scripts so that you can do npm run yourScriptName instead.

Editor Support

Prepare Your Editor

All of the IDE plugins, including integration with error highlighting, autocomplete, and syntax highlighting are included inside of the built project.

Configure your EDITOR to load the Reason plugins from your instance of ReasonProject. See the instructions for Atom and Vim.

IDE support included.

The editor config above mostly exists to load the actual editor support, from the ReasonProject build. The only thing we need is to make sure the PATH contains all the important stuff from ReasonProject's build. There are two approaches: one continues to avoid global variables (as we've done so far), and the other doesn't.

Avoiding Global Paths

You can continue to develop entirely in the isolated sandbox without polluting global environment variables, by opening your editor within the sandbox environment:

npm run env -- vim
npm run env -- atom
npm run env -- mvim

Because you've prepared your editor to load editor support from the environment, npm run env -- yourEditor ensures that your editor will find the editor support in your environment variables.

Note: If you use atom, and already have opam installed, then there's a known issue where atom has problems loading, but you can fix it easily by commenting out any part in your bashrc that sources opam environments. We will come up with a long term solution at some point.

Using Global Paths

Pure sandboxed based development doesn't always work for certain workflows. (prefixing all commands with npm run may not work well). In that case, you can easily inject your successfully built project's environment into the global PATH, by putting the following in your .bashrc:

# In your .bashrc
pushd ~/pathTo/ReasonProject/ && \
  eval $(~/pathTo/ReasonProject/node_modules/.bin/dependencyEnv) && \
  popd

Developing Your Project

Making It Yours

ReasonProject is meant to be the starting point of your own project. You'll want to make use of existing libraries in your app, so browse the growing set of opam packages ported to npm under opam-alpha. If there's something that hasn't yet been ported from opam, make a pull request to this repo and the package will automatically be ported (as soon as the daemon picks it up).

Add Another Dependency

Option 1: Install a dependency into the project sandbox, and use --save so that your package.json is updated.

npm install --save @opam-alpha/cstruct

Option 2: Edit the package.json manually to include your new dependency and run npm install.

Note: Sometimes options 1 and 2 above fail because some other dependency that is rebuilt as a result of the install was not designed to build in an idempotent manner. In that case, just add the new dependency to your package.json "dependencies", rm -r node_modules, and then run npm install. This installs from a clean slate.

Note: opam-alpha is "alpha" - we may move to a new namespace opam-beta once we apply the lessons we've learned from opam-alpha. All the should exist as they are, but a next generation opam-beta universe on npm would have everything opam-alpha has (and then some). The work to upgrade your projects will likely be minimal.

This merely adds and builds the dependency. It doesn't mean your build system will know to link to it. Accomplishing that is build system dependent, but if using the example build system (rebuild, which is based on ocamlbuild), you can get an idea for the options by doing npm run buildHelp. Typically you need to configure the reasonBuild entry in package.json to add the -pkg dependencyPackage. Consult your dependency's docs.

Add Your Own Scripts

npm allows scripts to be specified in your project's package.json. These scripts are a named set of commands. A few scripts have special meaning, such as the postinstall script.

The postinstall script is how your project compiles itself. It is guaranteed that the postinstall script executes any time you run npm install in this package, or any time another package installs you as a dependency. You're also guaranteed that your postinstall script is executed after all of your dependencies' postinstall scripts.

You can add new named scripts in the package.json scripts field. Once added, you can then run them via npm run scriptName from within the project root.

Making Sure Your Scripts See The Environment

eval $(dependencyEnv) is commonly used in these scripts. This eval statement augments the environment for the duration of the named script, which ensures that important binaries (such as refmt) are in the PATH.

When the entire purpose of developer tools is to generate a binary (such as a compiler) to be included in your PATH, or produce a library whose path should be specified in an special environment variable, it's almost like the environment variable is the public API of that package. dependencyEnv allows your script to see the environment variables that your immediate dependencies wanted to publish as their public API. You can learn how packages can publish environment variables in the dependency-env repo.

Multiple Projects

You can have multiple clones/forks/builds of ReasonProject - one for each of your projects. When you make changes, you can share the project easily with anyone else because you are modelling all dependencies via package.json. If also using the global environment, you may want to designate one special ReasonProject, that is only used for augmenting the global path.

Creating Libraries

ReasonProject sets up your environment for building an application. We haven't yet mentioned how to then share your work with other people as an npm dependency itself. More coming soon.

Troubleshooting

In general, if something goes wrong, try deleting the local node_modules directory that was installed, and then try reinstalling using npm install -f (to avoid using a stale cache). Then if that doesn't work, follow the following steps to debug your specific failed dependency.

Debugging Failed Dependencies

When npm install fails to install one of your dependencies, it's typically because a postinstall step of a package has failed. Read the logs to determine which one is failing. npm will delete the directory of the failed package so the failed install won't be in node_modules, but you can usually try to reinstall it explicitly, and debug the installation. Suppose the @opam-alpha/qcheck package failed to install. Let's recreate the failure so we can debug it.

#####Do a dry run: Let's see what an npm install for this package would install. The --dry-run flag avoids actually installing anything.

npm install --dry-run @opam-alpha/qcheck

In my project, it says it would only need to install the following packages. That's because all of the other ones must have already been installed in node_modules.

# Output
test@1.0.0 /Users/jwalke/Desktop/tmp
└─┬ @opam-alpha/qcheck@0.4.0 
  └── qcheck-actual@0.4.0 (git://github.com/npm-opam/qcheck.git)

Note: Sometimes it won't traverse git dependencies to find all the potentially installed package. That's okay.

Install Source Without Building

So we want to install that now, but without executing the install scripts so we pass the --ignore-scripts flag. Without that flag, it would fail when running the scripts again, and then remove the package again!

npm install --ignore-scripts @opam-alpha/qcheck@0.4.0

This will just install the source code, and let us know what it actually installed.

Try The Build Manually, In Place

Now, make sure npm didn't do something weird with installing new versions of package that didn't show up in the dry run, and make sure it installed things as flat as possible in node_modules, as opposed to nesting node_modules for compiled ocaml packages inside of other node_modules. Ideally, everything is a flat list inside the ReasonProject/node_modules directory.

cd into the package that was failing to build correctly (it was actually the qcheck-actual package in our case). Run the build command in package.json's postinstall field by doing npm run postinstall.

cd node_modules/qcheck-actual
npm run postinstall

Now the package should fail as it did when you tried to install your top level project, but without removing the packages, so you can debug the issue, fix it, then try rebuilding again. Usually you need to reconfigure the problematic package, or fix the build script. Fix it, and push an update for the package.

Finally, once you've pushed a fix to the package for the issue, rm the entire project's node_modules directory and re-run npm install from the top again. This just makes sure you've got everything nice and clean as if you installed it for the first time.

npm run whereisocamlmerlin

sverrejoh/ReasonProject