walkmap.edge
Essentially the specification for things we shall consider to be an edge. An edge is a line segment having just a start and an end, with no intervening nodes.
edge?
(edge? o)True if o satisfies the conditions for a path. A path shall be a map having the keys :start and :end, such that the values of each of those keys shall be a vertex.
path->edges
(path->edges o)if o is a path, a polygon, or a sequence of vertices, return a sequence of edges representing that path, polygon or sequence.
unit-vector
(unit-vector e)Return an vertex parallel to e starting from the coordinate origin. Two edges which are parallel will have the same unit vector.