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Forms and Evaluation

A form is either any single expression that appears in the file. A GDL file consists of a sequence of forms. Most forms of interest will be lists whose first element is a symbol identifying the form. For instance, a form beginning with the symbol side declares a side object. When the file containing such a form is read, Xconq will create a side object and fill in any properties as specified by the form. (Properties are like properties or attributes - most GDL objects have some.)

In most contexts, Xconq will evaluate an expression before using it, such as when filling in an object's property. Numbers and strings evaluate to themselves, while symbols evaluate to their bindings, as set by set or define. Lists evaluate to a list of the same length, but with all the elements evaluated, unless the first element of the list is a function. In that case, the remaining elements of the list are evaluated and given to the function, and its result will be the result.


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