Computing with text-graphic forms occurs when text-graphic patterns are used to direct the
manipulation of other text-graphic patterns. The form chosen to demonstrate this kind of
computation is the VennLISP expression created in the previous example. Before evaluation
can proceed, the assignment forms in Figure 3 need to be executed in order to pack the
with the visual name-shapes that are the synonyms for each of the textual function names.
Next, within the programming environment portrayed in Figure 4, the form can be
submitted for evaluation. First the form is made into the body of a lambda expression and
bound to the VennLISP nameshape for
MEMBER? (since the form represents one
defintion of the membership test, returning or some tail of the
second argument). Then the other two assignment forms are evaluated in order to bind the
left ear to the mouth and to the visual object george. And
finally, when the function call in the upper left is evaluated, the result is returned at the
cursor in the upper right.
Figure 5 shows the tree structure for the visual forms involved.