The draw function outputs a random object of size n in the class  defined by the specification spec, with uniform distribution among all objects of the same size.

In the case of structures, the draw function returns an object of size n, or an object chosen from all possible sizes, or an object of the default size for that structure, if the size was not specified.

Use the string 'allsizes' which is available only for predefined structures when the object is chosen from all possible sizes.

The count function returns the number of such objects.

To learn how to write a grammar specification, see combstruct[specification].

For a list of available structures, see combstruct[structures].