Penrose Domain Specific Language (DSL): Linear Algebra

This is a domain specific language (DSL) repository that is part of the penrose library and is intended for install in penrose. It includes the domain specific language (DSL) file(s) for the Linear Algebra domain. The visual portion of the site is meant to be human friendly, while the API served at /api.json is a programmatically accessible endpoint to retrieve the style.

Setup

1. Install Jekyll locally. For Ruby, I recommend rbenv.
2. Install Jekyll dependencies with bundle install
3. To serve the development server run bundle exec jekyll serve

Folders Included

If you aren't familiar with the structure of a Jekyll site, here is a quick overview:

Design Files

The design file trios refer to substance, domain specific language (dsl) and style files that can be used to generate diagrams.

• _dsl: includes files that are used in "production" examples. Previous versions coincide with commits. These files get rendered into the static API, and each design has its own page for images, documentation and example usage.
• _dev: Any "work in progress" files.
• _examples is a collection of subfolders (a grouping of designs) from other penrose-lib repositories to exemplify the usage of this dsl.

Documentation and Site

• _config.yml is the primary configuration file for the site. Variables in this file render as {{ site.var }} in the various html includes and templates.
• _layouts are base html templates for pages
• _includes are snippets of html added to layouts
• pages are generic pages that aren't considered docs
• assets includes all static assets

How Do I...

Develop new style, substance, or domain specific language files?

You can use the folder _dev to keep these works in progress. They won't be rendered into the API.

Add a new style or domain specific language?

1. Add source files

The production dsls are under _dsl.

2. Add a domain page

Each file that ends with dsl should have a corresponding markdown file to describe it. Here is an example of the frontend matter for the linear-algebra.dsl:

---
title: Linear Algebra
category: dsl
order: 1

dsl: linear-algebra.dsl
branch: master
---

## Usage

...

The notes that you add to this file are important for users to understand usage, although not required for the API. It's a content area that renders markdown, so you should feel free to write as much as you think is useful.

3. Update the changelog

The files in _posts render into the repository changelog. Please add a new entry with meaningful information when you add, remove, or otherwise change content. This isn't a perfect way to track changes, but it's a best effort.

Special Attributes

We have some special attributes, in case they are needed. You can optionally add the following to the page frontend matter:

• hidden: If you have a design trio that was considered production and you need to hide it from the API for some reason (you can imagine an emergency fix is needed and you want to take it offline, but perhaps not completely remove it from the documentation pages) you can add "hidden: true" to the frontend matter. It will render (for a human) on the site, but not be available via the API.

API Interaction

The above details how to add content, and by simply adding files to _dsl. They will automatically be added to the API. But where is it? You can find the API at the /api.json endpoint served by the repository, and linked from the main page. If I'm running a local server, here is how to access it via python:

import requests
url = "http://localhost:4000/dsl-linear-algebra/api.json"
response = requests.get(url)

Did we get a 200 (successful) response?

response
<Response [200]>

response.status_code
200

Let's look at our data.

results = response.json()

There are keys for a unique id (the Github repository url), a set of links, and then the data (each trio that has been added).

results.keys()
# dict_keys(['id', 'links', 'data'])

Here is the complete data:

{
    "id": "penrose-lib/dsl-linear-algebra",
    "links": {
        "self": "http://localhost:4000/dsl-linear-algebra/api.json",
        "url": "https://www.github.com/penrose-lib/dsl-linear-algebra"
    },
    "data": [
        {
            "name": "dsl/linear-algebra",
            "id": "penrose-lib/dsl-linear-algebra:dsl/linear-algebra",
            "dsl": "http://localhost:4000/dsl-linear-algebra/dsl/linear-algebra.dsl",
            "dsl_raw": "https://raw.githubusercontent.com/penrose-lib/dsl-linear-algebra/master/dsl/linear-algebra.dsl",
            "dsl_url": "https://raw.githubusercontent.com/penrose-lib/dsl-linear-algebra/<VERSION>/dsl/linear-algebra.dsl",
            "group": "dsl"
        }
    ]
}

Let's walk through each component.

The Unique Resource Identifier

results['id']
'penrose-lib/dsl-linear-algebra'

This is the unique resource identifier for the dsl file. It is in reference to the Github organization (penrose-lib) and the repository name (dsl-linear-algebra). We can have confidence that the metadata to learn more about the dsl file will always be served at the Github Pages for that site, at https://penrose-lib.github.io/dsl-linear-algebra/api.json.

Links

Per the json API specification, we add a set of links so if a user saves the endpoint data as json or other, he or she can return to find the original source.

results['links']
{'self': 'http://localhost:4000/domain-linear-algebra/library.json',
 'url': 'https://www.github.com/penrose/domain-linear-algebra'}

The reason that we see localhost in this example is because we are running the Jekyll server locally.

Data

Finally, the data itself! This is where the user finds the link to the DSL file (the "dsl" attribute), along with a dsl_url that can have <VERSION> substituted for a particular commit. When tools are using this repository and looking for a particular version or branch, that string should be replaced with the version or branch to reference the file.

results['data'][0]
{'dsl': 'http://localhost:4000/dsl-linear-algebra/dsl/linear-algebra.dsl',
 'dsl_raw': 'https://raw.githubusercontent.com/penrose-lib/dsl-linear-algebra/master/dsl/linear-algebra.dsl',
 'dsl_url': 'https://raw.githubusercontent.com/penrose-lib/dsl-linear-algebra/<VERSION>/dsl/linear-algebra.dsl',
 'group': 'dsl',
 'id': 'penrose-lib/dsl-linear-algebra:dsl/linear-algebra',
 'name': 'dsl/linear-algebra'}

dsl

This is the production URL for the dsl file, served from Github pages.

dsl_raw

This is the link to the raw file served by raw.githubusercontent.com. You'll notice a branch (master) rendered into the url, and this is specified in the markdown metadata by the creator to indicate the raw file is served from the master branch. Serving production from master branch is a standard that should be upheld.

dsl_url

This is the same URL, but "master" has been replaced with a string "" that a client is intended to replace with a branch, tag, or commit to get a direct link to a specific version of the file.

id

Here is where we get the full URI for the dsl file:

penrose-lib/dsl-linear-algebra:dsl/linear-algebra'

The beginning portion refers to the repository URI (penrose-lib/dsl-linear-algebra) and the second portion refers to the component type (dsl) and also the url where it's served from. This is the formula for a Penrose Library URI:

<organization>/<repository>:<element>/<name>@<version>

The <element>/<name> together make up the namespace.

Generate My Own Domain?

We will be generating a cookie cutter template to help you do this! See penrose/cookiecutter-dsl to get started.