enso/docs/distribution/packaging.md

layout	title	category	tags	order
developer-doc	Enso Libraries Packaging	distribution	packaging distribution layout	2

Enso Libraries Packaging

Given the nature of Enso as an open-source programming language and platform, it is crucial that we provide users with an extensible package management system. This document describes the current state of our packaging efforts, as well as future directions and enhancements to it.

• Enso Package Structure
  • The src Directory
  • The polyglot Directory
  • The package.yaml File
  • The visualization Directory
• Build Reproducibility

Enso Package Structure

The general directory structure of an Enso package is as follows:

My_Package
├── package.yaml
├── polyglot
│   ├── java
│   │   └── jar.jar
│   └── js
│       └── library.js
├── src
│   ├── Main.enso
│   └── Sub_Module
│       ├── Helper.enso
│       └── Util.enso
├── visualization (optional)
│   └── ...
└── data (optional)

The src Directory

The src directory contains all Enso sources, organized in a hierarchical structure. The structure of this directory dictates how particular modules are imported in all of Enso code.

Note that all files and directories in this subtree must be named according to the Enso style for referent names (i.e. Upper_Snake_Case, see the syntax specification).

A file located at the path My_Package/src/Sub_Module/Helper.enso will be imported like so:

import My_Package.Sub_Module.Helper

Please note the following:

• The name of the package appears as the first segment of the name.
• The package name is not specified by the containing directory's name, but rather it is described in the package.yaml file.

The exact transformation is as follows:

1. The name of the package becomes the first segment of the qualified module name.
2. Any subdirectories on the path from the src directory to the source file are appended as consecutive segments.
3. The name of the source file, with the .enso extension stripped, becomes the last segment.

The polyglot Directory

The polyglot directory contains per-language subdirectories containing files used by the supported polyglot languages. The contents of each subdirectory is specified on a per-language basis, in the polyglot documentation.

The data Directory

The data directory contains any data files and resources that the user needs quick access to. Allows referring to resource files in a location-independent way, by using the Enso_Project.data method.

The package.yaml File

package.yaml describes certain package metadata, such as its name, authors and version. It also includes the list of extra dependencies of the package (dependencies that are not present in the resolver or need a version override). The following is an example of this manifest file.

license: MIT
name: My_Package
version: 1.0.1
edition:
  extends: 2021.3
  enso-version: 0.2.12
  libraries:
    - name: Foo.Bar
      version: 1.2.3
      repository: main
prefer-local-libraries: false
authors:
  - name: John Doe
    email: john.doe@example.com
maintainers:
  - name: Jane Doe
    email: jane.doe@example.com

The following is the specification of the manifest fields. Fields marked as Optional (required for publishing) are completely optional during development - if not specified, their default values will be used. However, they must be specified before publishing the package. A package missing any of these fields cannot be published.

license

Optional (required for publishing) String: The short license name of this package. Defaults to None, meaning the package is not safe for use by third parties.

edition

Optional (required for publishing) Edition: Defines the Edition settings of the package that determine the engine version and library resolution settings. It is a sub-setting that can consist of multiple fields, see the Edition documentation for the format description.

The field was added in version 0.2.12 as a replacement for enso-version as it supersedes its functionality.

If the edition field is not specified, a default edition is used.

enso-version

Deprecated String: Specifies the Enso version that should be used for this project. If not set or set to default, the default locally installed Enso version will be used.

The field was deprecated in version 0.2.12. Currently it is still supported, but the newer tools will migrate it to the edition format when the config is modified.

If old tools see a config file that includes an edition setting but does not include the engine-version (for example after the migration), they will fall back to using the default engine version - that is because old tools were not aware of the edition field, so they will simply ignore it.

If a config defines the edition field it should not define the engine-version field anymore, as that could lead to inconsistent engine version settings.

version

Optional (required for publishing) String: The semantic versioning string, in the major.minor.patch format. If not set, it defaults to dev (which can be used for development, but is not a valid version for publishing).

authors

Optional List of contacts: The name(s) and contact info(s) of the author(s) of this library.

A contact is of the form:

name: Contact Name
email: email@example.com

Both name and email fields are optional, but at least one of them has to be present.

maintainers

Optional List of contacts: The name(s) and contact info(s) of the current maintainer(s) of this library, in the same format as authors above.

prefer-local-libraries

Optional Boolean: A flag that tells the library resolver to prefer local library versions over the ones specified by the edition configuration. This is useful to make all local libraries easily accessible, but in more sophisticated scenarios individual local repository overrides should be used instead of that. See Library Resolution for more details.

If the flag is not specified, it defaults to false, delegating all library resolution to the edition configuration. However, newly created projects will have it set to true.

The visualization Directory

As Enso is a visual language, a package may contain a specification of how data can be displayed in various tools, for example Enso IDE. The Enso package structure may optionally contain a visualization directory which may contain visualization definitions.

For more information on how visualization definitions should work with the Enso IDE, see this example.

Build Reproducibility

It is crucial for any good development environment to provide reproducible builds, such that it is impossible for it to go wrong by mismatching library versions.

The actionables for this section are:

• Decide on the strategies of ensuring consistent library resolution. This may include hashing the downloaded versions of libraries and publishing stack-style resolvers for sets of libraries that are proven to work well together.