# Language Reference/Constants

From wiki.visual-prolog.com

### Constants Sections

A **constants** section defines a set of constants in the current scope.

ConstantsSection : constants ConstantDefinition-dot-term-list-opt

### Constant Definitions

A constant definition defines a named constant, its type, and its value.

ConstantDefinition: one of ConstantName = ConstantValue ConstantName : TypeExpression = ConstantValue

ConstantName: LowerCaseIdentifier

The **ConstantValue** should be an expression, which can be evaluated at compile time and it should have the type of the correspondent domain. The **ConstantName** should be a lower case identifier.

The TypeExpression can be omitted only for the following built-in domains:

- Numerical (i.e. integral or real) constants. In this case, the corresponding anonymous numerical domain is adopted for a constant (see the numerical domains for details).
- Binary constants.
- String constants.
- Character constants.

Example

constants my_char = 'a'. true_const : boolean = true. binaryFileName = "mybin". myBinary = #bininclude(binaryFileName).