Intelligent Image Processing Using Prolog. The “flow of control” in a Prolog program does not follow the normal convention of. It is possible to make very general statements in Prolog in a way that is not possible. Continuations and advanced flow control. After their first introduction to programming, many programmers don't think about flow control, since most programming languages have only a few simple flow control constructs. There are several types of non- local exits, each of which can be divided into two categories, structured and unstructured. If complex flow control is not naturally nested, imposing a nested structure on it can make it less readable, not more. Simple database code example//NOTE - - this code will not compile, but that's on purpose. To do this in the Java language, you would rewrite the code as follows. Listing 2. Simple database function with exception handlingimport java. Simple database example with application- level exception throwingimport java. The try and catch statements can be in any containing function as well. Exception handling has several major gotchas that are outside of the scope of this article, but some of the Resources can give you some guidance on these. A generator is able to . Simple Python generator program#This is our generator function. Simple logic program in Prologlikes(john,sports). However, sports isn't in brad's list of items. Continuation example(display. Calling the continuation will return the parameter as the return value to. Early exit from error conditions with a continuation(define a '(1 2 3 4 5)). Bookmark here. (call- with- current- continuation. Check to see if it is a number. Reactivating a stack frame with continuations; ;Global variable for the continuation. We are using let* instead of let so that we can guarantee. The continuation will be stored in . Exception exampletry . The desired expansion of a hypothetical exception macro; ;This establishes the throw function as globally available, but displays an. Macro to generate exception code; ;This establishes the throw function. Bad interactions of continuations; ;Uses previously defined try/catch macro. Example using dynamic- wind(let (. For flow control to pass across the . Improved try/catch with dynamic- wind; ;This establishes the throw function as globally available, but displays an. The next section revisits some of the possible problems. Example of using a Python- style generator(define- syntax generator. A Prolog program can modify itself as it is. In Prolog no distinction between statements & method calls. Prolog Control Flow Example. For any prolog program. Control flow (the order of. Control flow is the ordering in program execution. Emphasis is on describing the information being processed by a program (COBOL, Prolog). Control: How the general program flow will be controlled. One is the procedure to return to the calling program, and the other is the current location where the generator is executing. Using backtracking in Scheme(let* (. Implementation of backtracking; AMB definition.
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