Karel was introduced by Richard Pattis in the book "Karel The Robot: A Gentle Introduction to the Art of Programming" (second edition 1994, first edition 1981).

This implementation takes the form of a collection of library procedures for PocketC. You write PocketC programs using these procedures and the library provides the display (as well as a world editor).

Since programs are compiled with PocketC you'll need the full version of PocketC, not the runtime only version.
For more information see http://www.winikoff.net/palm/Karel