An applicative language called HOPE is described and discussed. The underlying goal of the design and implementation effort was to produce a very simple programming language which encourages the construction of clear and manipulable programs. HOPE does not include an assignment statement; this is felt to be an important simplification. The user may freely define his own data types, without the need to devise a complicated encoding in terms of low-level types. The language is very strongly typed, and as implemented it incorporates a typechecker which handles polymorphic types and overloaded operators. Functions are defined by a set of recursion equations; the left-hand side of each equation includes a pattern used to determine which equation to use for a given argument. The availability of arbitrary higher-order types allows functions to be defined which 'package' recursion. Lazily-evaluated lists are provided, allowing the use of infinite lists which could be used to provide interactive input/output and concurrency.

This paper discusses ZBMs technical contributions to high level programming languages from the viewpoint of speciJic languages and their contributions to the technology. The philosophy used in this paper is that it is the appropriate collection of features in a language which generally makes the contribution to the technology, rather than an individual feature. Those ZBM languages deemed to have made major contributions are (in alphabetical order) APL, FORTRAN, GPSS, and PLII. Smaller contributions (because of lesser general usage) have been made by Commercial Translator, CPS, FOR-MAC, QUIKTRAN, and SCRATCHPAD. Major contributions were made in the area of formal definition of languages, through the introduction of BNF (Backus-Naur Form) for defining language syntax and VDL (Vienna Definition Language) for semantics. 1. introduction This paper delineates some of IBM’s technical contributions to high level programming languages, with some discussion of related work outside IBM to provide perspective. Section 2 provides a brief but broad chronological tracing of high level language developments, and Section 3 discusses the two very early IBM languages. Of