RLAI Reinforcement Learning and Artificial Intelligence (RLAI)

tiny-crystal project part 4: virtual connections

Implement the basic virtual connection making names virtually-connect and virtually-connect-from. Implement these as scheme procedures that are called from the lookup procedure you wrote in part 2.  Brief descriptions of the function of virtually-connect can be found on page 3 of the crystal vocabulary notes, and virtually-connect-from is the same except that the starting vertex is specified, as in connect-from. Remember that here in tiny crystal we are using the fixed-length forms, as in:

      (virtually-connect '(sum of squares ? x y)
        '(+ (square (x))
            (square (y))))
 (virtually-connect-from (my-utilities) '(square ? x)
    '(* (x) (x)))

You may want to also implement the short forms vconn and vconn-from.


Convert virtually-connects to virtually-connect-froms to that you only need to implement one of them.

Package the virtual part of a virtual connection up into a special kind of nonterminal vertex called a stub.  A stub is like the procedure structure ('procedure params body environment) in the Q&D scheme interpreter in that it bundles all of the information needed to execute at a later time when the arguments or labels are available. In the crystal case we need to bundle the name that will be called at the later time, the names of the labels it uses (formal parameters), and the path in which the virtual connection was made and should be called.  The only thing missing, to be provided when the vertex is accessed, is the actual labels when the connection is realized.  When these become available they can be popped on the path and then the name called with respect to the extended path.

testing - see main spec page

Changes since Nov 15:

The text was corrected to indicate that stub vertices are nonterminal, not terminal.

You may be able to implement these crystal primitives just like the other scheme primitives, like + or display.  This is permitted.

It would be better if virtually-connect returned the stub vertex. Then it could be used like a lambda. For example, (virtually-connect '(? x y) (+ (x) (y))) would return the unnamed stub vertex that takes in two numbers and returns their sum. 
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