CWTGF: pattern evaluating

Pattern Evaluating

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 vizalist with the visual name-shapes that are the synonyms for each of the textual function names.


 

Figure 3.


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 4.



 
 

Figure 5 shows the tree structure for the visual forms involved.


 

Figure 5.