Home
Concepts
This section of the documentation covers the use of Objects, Libraries and References, Notations, Styles and Types and how each is created, edited and used in the Sym application.
Styles
Each notation refers to a stylesheet. Stylesheets define Styles. Styles are used in two places. First, they can be used to style text. Second, they can be used to style parts of an expression in a rendering. You can create new style and new stylesheets.

Concepts
This section of the documentation covers the use of Objects, Libraries and References, Notations, Styles and Types and how each is created, edited and used in the Sym application.
- Objects
  An object is the basic building block of all of the symbolic content contained in a document - every term in every symbolic expression in Sym is an instance of an object. Many of the objects used in Sym have an object definition that specifies how the object looks and behaves, but it's also possible to create objects that don't have object definitions. All objects are identified by their name and object names are always defined in a specific namespace. All object definitions contain a type definition. Optionally, objects can also contain Properties, Clauses, Renderings, and a Description.
- Library Locations and References
  Locations are used to manage groups of libraries and documents. The purpose of locations is to make documents portable from one machine to another. To do that, locations can be online as well as on your local machine. If a document references online libraries, the required libraries will be downloaded automatically when the document is opened.
- Notations and Rendering
  The purpose of notations is to make it possible to easily change the way expressions are displayed. Notations are assigned to Document Modules, Unit Test Modules and Object Modules. The notation assigned determines which renderings are selected for each expression in the module.
- Styles
  Each notation refers to a stylesheet. Stylesheets define Styles. Styles are used in two places. First, they can be used to style text. Second, they can be used to style parts of an expression in a rendering. You can create new style and new stylesheets.
  - Creating Styles
    Styles are defined in Stylesheets. Stylesheets are functions that return the style settings for a given class name. In this topic, we will cover adding new styles to an existing stylesheet. Creating new stylesheets is covered separately.
  - Creating Stylesheets
    Stylesheets determine the fonts and sizes that are used when objects are displayed. They are designed somewhat like cascading style sheets. Creating a new stylesheet just involves creating a new object definition for the new stylesheet.
  - Style Functions
    Part of the process of generating a rendering expression for any expression is getting and applying the styles for the expression.
- Types
  Every term in every expression in a Sym document has a type assigned to it. Every object definition has a type definition as one of its components. Since type definitions can include things like type variables, Sym uses a type inferencing process to determine the explicit types assigned to each term in every expression.

Styles

Each notation refers to a stylesheet. Stylesheets define Styles. Styles are used in two places. First, they can be used to style text. Second, they can be used to style parts of an expression in a rendering. You can create new style and new stylesheets.

The process of styling an expression or text is similar to the way that cascading style sheets that are commonly used in HTML. The current stylesheet defines the styles that are available, the objects in the document refer to these styles.

The main differences between the stylesheets in Sym and the cascading style sheets used in HTML are:

Stylesheets in Sym don't cascade
Stylesheets in Sym are functions. The parameter passed to the function is a ClassName, the expression returned by a stylesheet function is a Style. It contains the styles that should be applied for that class. The styles include things like the font, font style, and so on.

The current stylesheet is determined by the notation. The Stylesheet property can be attached to the object definition of a notation to set the stylesheet that is used in that notation.

You can create new stylesheets (see Creating Stylesheets) which can define both new and existing styles or you can add styles to an existing stylesheet (see Creating Styles) by extending a stylesheet function.