A light-touch approach to designing, building and describing visualization. Here you will find
- Explanations of the literate visualization process.
- Tutorials for working with litvis, Elm and elm-vega.
- Examples of literate visualization.
- Narrative Schemas to help you write literate visualization documents.
- Packages for developers working with litvis and NPM.
Litvis documents can be viewed and created in either the Atom or VS Code editors:
If you don't have it already, install Node.js. This will allow you to use npm, used for installing some of the other necessary software.
npm install --global elm prettier prettier-plugin-elm
If you cannot install with npm because of 'EACCES write permission errors', see these instructions on how to prevent them.
From within the editor, install litvis and Prettier extensions:
Atom → Preferences → Install(or
File → Settings → Installon Windows) In VSCode:
View → Extensions
markdown-preview-enhanced-with-litvisand then click the
installbutton next to the returned result. This may take a few minutes on a slow network connection.
prettier - Code formatter(VSCode) and then click the
installbutton. This extension will help you format litvis documents as you edit them.
elm(VSCode) and then click the
installbutton. This extension enables syntax highlighting for Elm source in code blocks.
Atom users should also search for
language-markdownand click the
Atom users: you may want to disable Atom’s standard markdown preview tool by going to
Preferences → Packages(or
File → Settings → Packages), searching for
disable. You may also wish to disable
spell-checktoo so that misspelled words are not confused with coding errors.
When you create your first document in Atom, you may be asked to install further dependencies such as
busy-signal. Install these and any other dependencies if requested.
‘Hello world’ in literate Elm
Adding litvis attribute
```elm blocks in markdown automatically compiles and executes the code in real time.
r) is the simplest way to see the result.
Simple litvis chart
Code referencing across blocks
By default, litvis code blocks share the same execution context, which means that an Elm symbol defined in one block and can be referenced in another block. It is not necessary to maintain the order of blocks to make referencing work.
Code referencing with triple hat notation
Symbols from Elm code blocks can be referenced in any part of the markdown using triple hat notation (
Code referencing with parameters
Triple hat references accept parametrized function calls, which makes it easy to combine text with graphics and produce families of related graphics. This means that small multiples and sparklines are straightforward.
json makes it possible to look into generated vega-lite specs.
These attributes follow the same ordering rules as
interactive to a code block with
v or a triple hat reference makes visualizations live if interaction is described within
User input controls can be added to the document, if desired.
Mutliple execution contexts
Although a single Elm execution context may be sufficient in many litivs narratives, context isolation may be desired in some cases.
A number of code block attributes such as
siding enable fine-grained control of Elm symbol visibility, thus making it easier to accomplish certain tasks.
s) is a shortcut for
This keyword makes previously defined symbols in
default context available within the code block, but avoids name clashes with the following blocks.
A litvis narrative can be split between multiple markdown documents, where each document
follows its parent.
This enables routine use of parallel branching narratives that assemble and structure document trees.
Each branch in a tree can represent alternative potentially competing designs each with their own rationale.
A litvis narrative can be linked to a set of YAML files, which define
These narrative schemas can be thought of as an analogue of schemas more usually found in declarative programming contexts such as JSON and XML schema.
The purpose of the schema is to provide a set of structured guidelines to assist in writing the narrative content around a visualization design.
This can be thought of as form of scaffolding to assist in the process of design exposition.
Schemas can be used to validate litvis documents.
A litvis document that is being previewed is constantly checked against various issues. These issues are displayed in the editing environment and help with debugging. If a visualization has been successfully rendered before the issue had occurred, its old preview is shown to avoid unwanted markup reflows.
Automatic code formatting
Litvis integrates with Prettier and its Elm plugin, which enables seamless document formatting as the narrative is being written. A file is automatically prettified on save or when the Format command is explicitly called. Formatting keeps litvis files in a readable and maintainable state, which eases collaboration and reduces distraction from the higher-level tasks.