Prehistory of the Asf+sdf System (1980{1984)

The rst stages of the development of the ASF+SDF system are discussed. 1 Monolingual beginning Our work on programming environments started in 1980 with the design of a dedicated environment for the Summer programming language 1], an object-oriented language with class deenitions. Rather than a dedicated Summer environment, the general concept of a monolingual environment emerged 2]. In such an environment, a single language is used in diierent modes. More speciically, we investigated the requirements an integrated command/programming/debugging language would have to satisfy. Since Summer had not been designed with this particular purpose in mind, it is not surprising that a monolingual environment for Summer would have involved a revision of the language. This may have been one of the reasons we never \instantiated" the monolingual concept for Summer, but there were other, more important, ones: