The Fortran programming language: recent developments and a view of the future

Abstract

Fortran has been in use for some 25 years, and has remained the most widely used programming language in spite of challenges from many new arrivals in the field. An official American National Standard for the language was adopted in 1966 and revised in 1978.The 1978 Fortran standard, known as Fortran 77, introduced "structured" branching, replaced Hollerith with a character-string data type, changed the minimum trip-count for the DO loop to zero, and established compromise forms for many of the variants that had developed since 1966. Compilers for this current standard version of Fortran became widely available in 1980 and 1981. Fortran 77 will remain in wide use through the decade of the 1980's.Looking toward the 1990's, efforts are now under way to modernize and further extend the Fortran language. A significant part of this modernization consists of removing (to a "Fortran 77 Compatibility Module"), and replacing with modern equivalents, many of the old features such as: arithmetic IF; assigned and computed GO TO; statement functions; DIMENSION declarations; ENTRY and alternate return features; and the label-delimited looping construct. An optional replacement for the punched-card oriented source program form will also become available.Features to be added in the Fortran of the 1990's include: whole-array expressions and assignment; precision specification for REAL data; inhomogeneous data structures; and a CASE control structure. A modular language architecture is contemplated, which will facilitate adding major extensions to the language in special application areas.