This paper describes the Oz Explorer and its implementation. The Explorer is a visual constraint programming tool intended to support the
development of constraint programs. It uses the search tree of a
constraint problem as its central metaphor. Exploration and
visualization of the search tree are user-driven and interactive. The
constraints of any node in the tree are available first-class:
predefined or user-defined procedures can be used to display or analyze
them. The Explorer is a fast and memory efficient tool intended for the
development of real-world constraint programs.
The Explorer is implemented in Oz using first-class computation spaces.
There is no fixed search strategy in Oz. Instead, first-class
computation spaces allow to program search engines. The Explorer is
one particular example of a user-guided search engine. The use of
recomputation to trade space for time makes it possible to solve large
real-world problems, which would use too much memory otherwise.