For those of you who don't like libraries, I included a library-free version in a self-contained sketch, "MLX90642_standalone.ino". The functions available in the library include: bool ...
The library is experimental as the functionality is not tested with hardware yet. The AD5231 is a single channel, 10 bit = 1024 step, SPI based potentiometer, the AD5235 is a dual channel version.