nimble/readme.markdown

# Babel
Babel is a *beta*-grade *package manager* for the Nimrod programming language.

## Installation

You will need the latest Nimrod compiler from github to compile babel (version 0.9.2 may work).

Compile babel by executing: ``nimrod c -d:release babel``. Then simply install
babel by executing ``./babel install``. You should then add ``~/.babel/bin``
to your $PATH.

**Note**: On **Windows** you must rename ``babel.exe`` to ``babel1.exe`` and
subsequently run ``babel1.exe install``. This is because Windows will lock
the process which is being run.

## Babel's folder structure
Babel stores everything that has been installed in ~/.babel on Unix systems and 
in your $home/.babel on Windows. Libraries are stored in $babelDir/pkgs, and
binaries are stored in $babelDir/bin.

## Packages

Babel works on git repositories as its primary source of packages. Its list of
packages is stored in a JSON file which is freely accessible in the
[nimrod-code/packages repository](https://github.com/nimrod-code/packages).
This JSON file provides babel with the required Git URL to clone the package
and install it. Installation and build instructions are contained inside a
ini-style file with the ``.babel`` file extension. The babel file shares
the package's name. 

### Libraries

When babel installs a library it will copy all the files that it downloaded
into ``$babelDir/pkgs/pkgname-ver``. It's up to the package creator to make sure
that the package directory layout is correct, this is so that users of the
package can correctly import the package.

By convention, it is suggested that the layout be as follows. The directory
layout is determined by the nature of your package, that is, whether your
package exposes only one module or multiple modules.

If your package exposes only a single module, then that module should be
present in the root directory (the directory with the babel file) of your git
repository, it is recommended that in this case you name that module whatever
your package's name is. A good example of this is the
[jester](https://github.com/dom96/jester) package which exposes the ``jester``
module. In this case the jester package is imported with ``import jester``.

If your package exposes multiple modules then the modules should be in a 
``PackageName`` directory. This will allow for a certain measure of isolation
from other packages which expose modules with the same names. In this case
the package's modules will be imported with ``import PackageName/module``.

You are free to combine the two approaches described.

In regards to modules which you do **not** wish to be exposed. You should place
them in a ``PackageName/private`` directory. Your modules may then import these
private modules with ``import PackageName/private/module``. This directory
structure may be enforced in the future. 

All files and folders in the directory of where the .babel file resides will be
copied as-is, you can however skip some directories or files by setting
the ``SkipDirs``, ``SkipFiles`` or ``SkipExt`` options in your .babel file.
Directories and files can also be specified on a *whitelist* basis, if you
specify either of ``InstallDirs``, ``InstallFiles`` or ``InstallExt`` then
babel will **only** install the files specified.

#### Example library .babel file

```ini
[Package]
name          = "ProjectName"
version       = "0.1.0"
author        = "Your Name"
description   = "Example .babel file."
license       = "MIT"

SkipDirs = "SomeDir" ; ./SomeDir will not be installed
SkipFiles = "file.txt,file2.txt" ; ./{file.txt, file2.txt} will not be installed

[Deps]
Requires: "nimrod >= 0.9.2"
```

All the fields (except ``SkipDirs`` and ``SkipFiles``) under ``[Package]`` are 
required. ``[Deps]`` may be ommitted.

### Binary packages

These are application packages which require building prior to installation.
A package is automatically a binary package as soon as it sets at least one
``bin`` value, like so:

```ini
bin = "main"
```

In this case when ``babel install`` is invoked, babel will build the ``main.nim``
file, copy it into ``$babelDir/pkgs/pkgname-ver/`` and subsequently create a
symlink to the binary in ``$babelDir/bin/``. On Windows a stub .bat file is
created instead.

Other files will be copied in the same way as they are for library packages.

Binary packages should not install .nim files so you should include
``SkipExt = "nim"`` in your .babel file, unless you intend for your package to
be a binary/library combo which is fine.

Dependencies are automatically installed before building.

## Dependencies

Dependencies are specified under the ``[Deps]`` section in a babel file.
The ``requires`` key is used to specify them. For example:

```ini
[Deps]
Requires: "nimrod >= 0.9.2, jester > 0.1 & <= 0.5"
```

Dependency lists support version ranges. These versions may either be a concrete
version like ``0.1``, or they may contain any of the less-than (``<``),
greater-than (``>``), less-than-or-equal-to (``<=``) and greater-than-or-equal-to
(``>=``). Two version ranges may be combined using the ``&`` operator for example:
``> 0.2 & < 1.0`` which will install a package with the version greater than 0.2
and less than 1.0.

## Versions

Versions of cloned packages via git or mercurial are determined through
the repo's *tags*.

When installing a package which needs to be downloaded, after the
download is complete and if the package is distributed through a VCS, babel
will check the cloned repo's tags list. If no tags exist, babel will simply
install the HEAD (or tip in mercurial) of the repo. If tags exist, babel will
attempt to look for tags which resemble versions (e.g. v0.1) and will then
find the latest version out of the available tags, once it does so it will install
the package after checking out the latest version.

## .babel reference

### [Package]

#### Required

* ``name`` - The name of the package.
* ``version`` - The *current* version of this package. This should be incremented
  **after** tagging the current version using ``git tag`` or ``hg tag``.
* ``author`` - The name of the author of this package.
* ``description`` - A string describing the package.
* ``license`` - The name of the license in which this package is licensed under.

#### Optional

* ``SkipDirs`` - A list of directory names which should be skipped during
  installation, separated by commas.
* ``SkipFiles`` - A list of file names which should be skipped during
  installation, separated by commas.
* ``SkipExt`` - A list of file extensions which should be skipped during
  installation, the extensions should be specified without a leading ``.`` and
  should be separated by commas.
* ``InstallDirs`` - A list of directories which should exclusively be installed,
  if this option is specified nothing else will be installed except the dirs
  listed here, the files listed in ``InstallFiles``, the files which share the
  extensions listed in ``InstallExt``, the .babel file and the binary
  (if ``bin`` is specified). Separated by commas.
* ``InstallFiles`` - A list of files which should be exclusively installed,
  this complements ``InstallDirs`` and ``InstallExt``. Only the files listed
  here, directories listed in ``InstallDirs``, files which share the extension
  listed in ``InstallExt``, the .babel file and the binary (if ``bin`` is
  specified) will be installed. Separated by commas.
* ``InstallExt`` - A list of file extensions which should be exclusively
  installed, this complements ``InstallDirs`` and ``InstallFiles``.
  Separated by commas.
* ``srcDir`` - Specifies the directory which contains the .nim source files.
  **Default**: The directory in which the .babel file resides; i.e. root dir of
  package.
* ``bin`` - A list of files which should be built separated by commas with
  no file extension required. This option turns your package into a *binary
  package*, babel will build the files specified and install them appropriately.
* ``backend`` - Specifies the backend which will be used to build the files
  listed in ``bin``. Possible values include: ``c``, ``cc``, ``cpp``, ``objc``,
  ``js``.
  **Default**: c

### [Deps]/[Dependencies]

#### Optional

* ``requires`` - Specified a list of package names with an optional version
  range separated by commas.
  **Example**: ``nimrod >= 0.9.2, jester``; with this value your package will
  depend on ``nimrod`` version 0.9.2 or greater and on any version of ``jester``.

## Submitting your package to the package list.
Babel's packages list is stored on github and everyone is encouraged to add
their own packages to it! Take a look at 
[nimrod-code/packages](https://github.com/nimrod-code/packages) to learn more.

## Contribution
If you would like to help, feel free to fork and make any additions you see 
fit and then send a pull request.
If you have any questions about the project you can ask me directly on github, 
ask on the nimrod [forum](http://forum.nimrod-code.org), or ask on Freenode in
the #nimrod channel.

## About
Babel has been written by [Dominik Picheta](http://picheta.me/) and is licensed 
under the BSD license (Look at license.txt for more info).