The paper starts by giving a motivation for studying grammars in design and is based on considerations of style, discovery, and constructive techniques. This paper goes on to survey a variety of spatial grammar formalisms from an implementation standpoint. For each formalism, the salient computational issues pertaining to rule application are discussed. Two aspects of shape grammars are considered in detail: (a) the conditions for reversibility of shape rules, and (b) the recognition of planar shapes.