A Framework for Program DevelopmentBased on Schematic

Often, calculi for manipulating and reasoning about programs can be recast as calculi for synthesizing programs. The diier-ence involves often only a slight shift of perspective: admitting metavari-ables into proofs. We propose that such calculi should be implemented in logical frameworks that support this kind of proof construction and that such an implementation can unify program veriication and synthesis. Our proposal is illustrated with a worked example developed in Paulson's Isabelle system. We also give examples of existent calculi that are closely related to the methodology we are proposing and others that can be prootably recast using our approach.