A foreword to ‘Fundamental concepts in programming languages

being published here for the first time. Written in the autumn of 1967, it is based on the lectures given by Strachey at an International School in Computer Programming, held in Copenhagen in August 1967. Strachey intended the paper to be published in the proceedings of the School—but the proceedings never materialized, and Strachey’s paper has remained an unpublished preprint for more than three decades. It is, however, one of Strachey’s most significant and lengthy papers; widely circulated in the original typescript version, it has also been highly influential. Strachey’s paper starts with some philosophical remarks about the need to focus on semantic issues in the design of programming languages, and to “recognise and isolate the central concepts—things analogous to the concepts of continuity and convergence in analysis”. Strachey then proceeds to give a clear and incisive exposition of many of his insights into programming language design and formal semantics, covering the following main topics:r assignment commands, L- and R-values;r expression evaluation and environments;r commands and sequencing;r modes of parameter-passing and variable binding;r functions and routines as data items;r types and (parametric) polymorphism; andr compound data structures and pointers. He also indicates how to model some of these concepts using ‚-expressions. The style of semantics proposed by Strachey in this paper was further developed (and pu