The Fortran I compiler

uring initial conversations about the topic of this article, it became evident that we can't identify the top compiler algorithm of the century if, as the CiSE editors originally intended, we consider only the parsing, analysis, and code optimization algorithms found in undergraduate compiler textbooks and the research literature. Making such a selection seemed, at first, the natural thing to do, because fundamental compiler algorithms belong to the same class as the other algorithms discussed in this special issue. In fact, fundamental compiler algorithms, like the other algorithms in this issue, are often amenable to formal descriptions and, as a result, to mathematical treatment. However, in the case of compilers the difficulty is that, paraphrasing John Donne, no algorithm is an island, entire of itself. A compiler's components are designed to work together to complement each other. Furthermore, next to this conceptual objection , there is the very practical issue that we don't have enough information to decide whether any of the fundamental compiler algorithms have had a determinant impact on the quality of compilers. At the same time, it is almost universally agreed that the most important event of the 20th century in compiling—and in computing—was the development of the first Fortran compiler between 1954 and 1957. By demonstrating that it is possible to automatically generate quality machine code from high-level descriptions, the IBM team led by John Backus opened the door to the Information Age. The impressive advances in scientific computing , and in computing in general, during the past half century would not have been possible without high-level languages. Although the word algorithm is not usually used in that sense, from the definition it follows that a compiler is an algorithm and, therefore, we can safely say that the Fortran I translator is the 20th century's top compiler algorithm. The language The IBM team not only developed the compiler but also designed the Fortran language, and today, almost 50 years later, Fortran is still the language of choice for scientific programming. The language has evolved, but there is a clear family resemblance between Fortran I and to-day's Fortran 77, 90, and 95. Fortran's influence is also evident in the most popular languages today , including numerically oriented languages The Fortran I compiler was the first demonstration that it is possible to automatically generate efficient machine code from high-level languages. It has thus been enormously influential. This article …