LIST AND RECURSION USING VISUAL PROLOG 5.2 CODE
If you understand Assembly Language and intend to use this code for other (meta-programming) tasks, all you have to do is modify just a couple of lines in the code that follows. The only difference between the way it works for Visual Prolog and the way it might work for another Prolog (or -indeed- ANY programming language, using a ‘C’-calling convention) is the Visual-Prolog-specific structure of a LIST, which in Visual Prolog has a different form than in all other languages. However, this does not exist in Visual Prolog, which sacrifices such “luxuries” for speed (which is the reason I also often use ISO-Prolog compilers, such as LPA-WinProlog and SWI-Prolog).Īnyway… The code you are about to see can be useful more generally, as an example of Prolog meta-programming, implemented in Assembly Language. Now, in ISO-Prolog there is a standard predicate known as “univ”, written as “ =.“, which turns a list like into a predicate call such as PRED(ARG1,ARG2,…). here is an Assembly language predicate, that takes as inputs another (external) predicate’s memory-address and a ( Visual Prolog-) argument-list, and calls this (external) predicate, using the (arbitrary-length-) list of N arguments, as arguments of “arity N”:Īpply_func(PRED, ) PRED(Arg1,Arg2,…) They also have an intrinsic fascination in themselves, as general tools for Prolog meta-programming.Į.g.
Prolog even further, potentially valuable for a multitude of other purposes. Recently, I discovered some Assembly language techniques to enhance G.I.S. Code modifications could therefore be done very quickly and most mistakes were (semi-)automatically corrected by the interpreter’s own enhanced error-checking capabilities. Prolog produced immediate results, without any need for (often tedious) EXE-file compilation. Prolog for easy immediate experimentation: Coding in G.I.S. A multitude of extra predicates, implemented in pure Assembly language, became available through G.I.S. So, the only way to implement ISO-Prolog functionality in Visual Prologis to extend the “ PIE Interpreter” (and G.I.S. Of course, such attempts are inherently limited by the internal design of Visual Prolog compilers. Ever since I started using the Visual Prolog compilers (and the PDC Prolog compilers preceding them) I was fascinated by the possibilities of implementing additional ISO-Prolog functionality in Visual Prologthrough Assembly Language and ‘C’.
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