The Spineless Tagless G-machine is an abstract machine designed to support nonstrict higher-order functional languages. This presentation of the machine falls into three parts. Firstly, we give a general discussion of the design issues involved in implementing non-strict functional languages. Next, we present the STG language, an austere but recognisably-functional language, which as well as a denotational meaning has a well-defined operational semantics. The STG language is the "abstract machine code" for the Spineless Tagless G-machine. Lastly, we discuss the mapping of the STG language onto stock hardware. The success of an abstract machine model depends largely on how efficient this mapping can be made, though this topic is often relegated to a short section. Instead, we give a detailed discussion of the design issues and the choices we have made. Our principal target is the C language, treating the C compiler as a portable assembler. Version 2.5 of this paper (minus appendix) appe...

This is the final report on the GRASP project, carried out under SERC grants GR/F34671 and GR/F98444, at Glasgow University 1 2 . The project supported two Principal Investigators (Simon Peyton Jones and Phil Wadler), and three Research Assistants (Kevin Hammond, Cordelia Hall and Will Partain). Four research students have worked in close association with the project. 1 Summary The purpose of GRASP was to help get the technology of functional programming out of the lab and into the hands of practitioners, by producing robust and usable compilers and profilers for these languages, on both sequential and parallel systems. The main achievements of the project are as follows: ffl We have played a key role in the development of a common international non-strict functional language, Haskell (Hudak et al. [1992]). This standardisation effort has led directly to a considerable focussing of the international research community in these languages. More details about Haskell are given in Sect...