Constraint Handling Rules

Constraint Handling Rules (CHR) is a pure constraint logic programming language developed by Thom Frühwirth at the University of Koblenz-Landau in Germany. It is based on the idea of constraint logic programming, which extends logic programming with constraint solving. In CHR, constraints are first-class citizens and can be manipulated like any other data structures. The main difference between CHR and other constraint programming languages is that CHR does not have a dedicated constraint solver. Instead, the programmer has full control over the constraint solving process. This allows for a much more declarative style of programming, where the programmer can focus on what the program should do, rather than on how to do it. The CHR language has been designed with efficiency in mind. It is based on a small set of primitive operations, which can be combined to form more complex operations. The language is also statically typed, which allows for more efficient execution. CHR is a powerful tool for solving complex problems. It is particularly well suited for problems that involve a lot of data manipulation, such as data mining and machine learning.