Forms/3 implements a declarative approach to flow control combined with the time dimension in an
approach that the authors call “vectors in time”. With this approach, each vector defines a sequence of
objects that represent the value of that cell at different points in time. Returning to the sample form in
Figure 15, if X defines a time vector of numeric objects such as , then Y defines a time vector
. Forms/3 provides the programmer with explicit access to the time dimension, and so iteration
can be implemented very elegantly even with this declarative approach. Consider an example of Figure 16,
a form designed to compute nth Fibonacci number. Here, “earlier” is one of the time-based operations in
Forms/3.