Persistent hyper-programs

This work was supported by ESPRIT III Basic Research Action 6309 – FIDE 2 and SERC grant GR/F 02953.The traditional representation of a program as a linear sequence of text forces a particular style of program construction to ensure good programming practice. Tools such as syntax directed editors, compilers, linkers and file managers are required to translate and execute these linear sequences of text. At some stage in the execution sequence the source text is checked for type correctness and its translated form linked to values in the environment. When this is performed early in the execution process confidence in the correctness of the program is raised, at the cost of some flexibility of use. Persistent systems allow the persistent environment to participate in the program construction process. This raises the possibility of allowing the representations of source programs to include direct links to values that already exist in the environment. By analogy with hyper-text, where a piece of text contains links to other pieces of text, this source representation is called a hyper-program. This paper outlines how hyper-programming facilities may be provided within a persistent system, discusses advantages of the technique and proposes some outstanding research areas. The advantages of hyper-programming over conventional systems include the following: it allows more convenient program composition mechanisms; it allows earlier checking; it provides more flexible linking mechanisms; it allows more succinct program representations; and it allows procedure closures to be represented at a source code level.Postprin