Fortrancompatible

Fortrancompatible is an adjective used to describe software, libraries, interfaces, or programming environments that provide compatibility with Fortran. Such components are designed to interoperate with Fortran code or to adhere to Fortran language standards, enabling reuse of existing routines and data structures.

Key to Fortran compatibility are the language standards and interoperability mechanisms. The ISO Fortran standards, including Fortran 90/95/2003, define facilities for interfacing with other languages, notably through the ISO_C_BINDING module, which enables calling C from Fortran and vice versa. Modern compilers implement these features to maintain consistent data types, calling conventions, and name resolution.

Common use cases include invoking legacy Fortran libraries from C, C++, or Python, and exposing Fortran-implemented kernels as portable APIs. Tools such as f2py facilitate Python-to-Fortran interoperability, while LAPACK and BLAS provide Fortran-compatible numerical routines that are widely wrapped for other languages.

Limitations exist. Achieving complete Fortran compatibility across all standards is challenging, and vendor extensions or fixed-form source from earlier Fortran versions can hinder portability. Interoperability requires attention to storage order (Fortran uses column-major arrays) and data representations, as mismatches can introduce subtle bugs.

Examples of Fortran-compatible ecosystems include GNU Fortran (gfortran), Intel Fortran, and IBM XL Fortran, all of which support ISO_C_BINDING and cross-language interoperability. The term is also used in contexts describing APIs and interfaces designed to be accessible from Fortran programs.