An argument list comes from a rest argument. It's distinct from a normal {@see \ScssPhp\ScssPhp\Value\SassList} in that it may contain a keyword map as well as the positional arguments.

Although calculations can in principle have any name or any number of arguments, this class only exposes the specific calculations that are supported by the Sass spec. This ensures that all calculations that the user works with are always fully simplified.

A function reference captures a function from the local environment so that it may be passed between modules.

Numbers can have units. Although there's no literal syntax for it, numbers support scientific-style numerator and denominator units (for example, miles/hour). These are expected to be resolved before being emitted to CSS.

Strings can either be quoted or unquoted. Unquoted strings are usually CSS identifiers, but they may contain any text.

All SassScript values are unmodifiable. New values can be constructed using subclass constructors like new SassString. Untyped values can be cast to particular types using assert*() functions like {@see \ScssPhp\ScssPhp\Value\assertString}, which throw user-friendly error messages if they fail.