On the basis for ELF - An Extensible Language Facility

Computer language for data processing and information retrieva

Approaches to the determination of parallelism in computer programs

Approaches to the determination of parallelism in computer program

Evaluation of HAL/S language compilability using SAMSO's Compiler Writing System (CWS)

NASA/Langley is engaged in a program to develop an adaptable guidance and control software concept for spacecraft such as shuttle-launched payloads. It is envisioned that this flight software be written in a higher-order language, such as HAL/S, to facilitate changes or additions. To make this adaptable software transferable to various onboard computers, a compiler writing system capability is necessary. A joint program with the Air Force Space and Missile Systems Organization was initiated to determine if the Compiler Writing System (CWS) owned by the Air Force could be utilized for this purpose. The present study explores the feasibility of including the HAL/S language constructs in CWS and the effort required to implement these constructs. This will determine the compilability of HAL/S using CWS and permit NASA/Langley to identify the HAL/S constructs desired for their applications. The study consisted of comparing the implementation of the Space Programming Language using CWS with the requirements for the implementation of HAL/S. It is the conclusion of the study that CWS already contains many of the language features of HAL/S and that it can be expanded for compiling part or all of HAL/S. It is assumed that persons reading and evaluating this report have a basic familiarity with (1) the principles of compiler construction and operation, and (2) the logical structure and applications characteristics of HAL/S and SPL

A digital system design language

Imperial Users onl

Development of an MSC language and compiler, volume 1

Higher order programming language and compiler for advanced computer software system to be used with manned space flights between 1972 and 198

The effective application of syntactic macros to language extensibility

Starting from B M Leavenworth's proposal for syntactic macros, we describe an extension language LE with which one may extend a base Language LB for defining a new programming language LP. The syntactic macro processor is designed to minimise the overheads required for implementing the extensions and for carrying the syntax and data type error diagnostics of LB through to the extended language LP. Wherever possible, programming errors are flagged where they are introduced in the source text, whether in a macro definition or in a macro call. LE provides a notation, similar to popular extended forms of BNF, for specifying alternative syntaxes for new linguistic forms in the macro template, a separate assertion clause for imposing context sensitive restrictions on macro calls which cannot be imposed by the template, and a non-procedural language which reflects the nested structure of the template for prescribing conditional text replacement in the macro body. A super user may use LE for introducing new linguistic forms to LB and redefining, replacing or deleting existing forms. The end user is given the syntactic macro in terms of an LP macro declaration with which he may define new forms which are local to the lexical environments in which they are declared in his LP program. Because the macro process is embedded in and directed by a deterministic top down parse, the user can be sure that his extensions are unambiguous. Examples of macro definitions are given using a base language LB which has been designed to be rich enough in syntax and data types for illustrating the problems encountered in extending high level languages. An implementation of a compiler/processor for LB and LE is also described. A survey of previous work in this area, summaries of LE and LB, and a description of the abstract target machine are contained in appendices

Distributed Concurrent Persistent Languages: An Experimental Design and Implementation

A universal persistent object store is a logical space of persistent objects whose localities span over machines reachable over networks. It provides a conceptual framework in which, on one hand, the distribution of data is transparent to application programmers and, on the other, store semantics of conventional languages is preserved. This means the manipulation of persistent objects on remote machines is both syntactically and semantically the same as in the case of local data. Consequently, many aspects of distributed programming in which computation tasks cooperate over different processors and different stores can be addressed within the confines of persistent programming. The work reported in this thesis is a logical generalization of the notion of persistence in the context of distribution. The concept of a universal persistent store is founded upon a universal addressing mechanism which augments existing addressing mechanisms. The universal addressing mechanism is realized based upon remote pointers which although containing more locality information than ordinary pointers, do not require architectural changes. Moreover, these remote pointers are transparent to the programmers. A language, Distributed PS-algol, is designed to experiment with this idea. The novel features of the language include: lightweight processes with a flavour of distribution, mutexes as the store-based synchronization primitive, and a remote procedure call mechanism as the message-based interprocess communication mechanism. Furthermore, the advantages of shared store programming and network architecture are obtained with the introduction of the programming concept of locality in an unobtrusive manner. A characteristic of the underlying addressing mechanism is that data are never copied to satisfy remote demands except where efficiency can be attained without compromising the semantics of data. A remote store operation model is described to effect remote updates. It is argued that such a choice is the most natural given that remote store operations resemble remote procedure calls

The pragmatic formalization of computing systems relative to a given high-level language

Imperial Users onl

A survey of compiler development aids

A theoretical background was established for the compilation process by dividing it into five phases and explaining the concepts and algorithms that underpin each. The five selected phases were lexical analysis, syntax analysis, semantic analysis, optimization, and code generation. Graph theoretical optimization techniques were presented, and approaches to code generation were described for both one-pass and multipass compilation environments. Following the initial tutorial sections, more than 20 tools that were developed to aid in the process of writing compilers were surveyed. Eight of the more recent compiler development aids were selected for special attention - SIMCMP/STAGE2, LANG-PAK, COGENT, XPL, AED, CWIC, LIS, and JOCIT. The impact of compiler development aids were assessed some of their shortcomings and some of the areas of research currently in progress were inspected