Using Constraint Handling Rules

## 8.2 Using Constraint Handling Rules

Here are the steps to be taken from writing to using CHRs:

- Write a CHR program in a file File`.chr`.
- In ECLiPSe, load the `chr` library with the query `lib(chr)`. It contains both the compiler and runtime system for CHRs. Now ECLiPSe is in coroutining mode.
- Compile your `chr` file into a `pl` file with the query `chr2pl(`File`).`
- In any ECLiPSe session, you can load a compiled constraint handler (`[`File`].`). The CHR library is automatically loaded to provide the necessary runtime environment. ECLiPSe is in coroutining mode.

You can compile your `chr` file and load the resulting `pl` file at once using the query `chr(`File`).`