From van Wijngaarden-Grammar to Aleph

摘要

The Aleph programming language is described. Aleph is an acronym for a language encouraging program hierarchy. Aleph is derived from an analysis of grammars rather than from that of programming languages. The notion of two-color Van Wijngaarden (VW) grammars is developed. The definition of affix grammars is recalled and the relationship with VW grammars is discussed. The flow-of-control rules that characterize the Aleph language and a central theorem useful in deriving assertions are presented. The analogy between grammars and programs and between parsing and problem solving is shown to be useful for designing a practical language that has some properties not usually found in programming languages.