Programming by example (PBE) from computation traces is hard to realize because of the difficulty to support
an interactive environment in which traces are easily written and edited. In this paper, we propose a new
approach to PBE called Computing-As-Editing Paradigm (CAEP) and describe a PBE system based on the
paradigm. The system has a two-dimensional language of constraints for writing computation traces.
Constraints represent rules that hold on every computation trace of the same program. In order to uniformly
treat rules on traces as constraints, we introduced a new kind of constraint called "iteration constraint", which
can represent iteration with fixed increments by simply pointing to the first and second iteration steps. We also
developed a new algorithm for inferring conditional expressions in iteration.