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The PRIF Committee is pleased to announce the publication of the Parallel Runtime Interface for Fortran (PRIF) Specification, Revision 0.7. The latest iteration of this specification represents the efforts of a collaborative design process involving multiple individuals across several institutions. The document is available here: <https://doi.org/10.25344/S46S3W> The PRIF specification is governed by a formal PRIF Committee. For more details, see: <https://go.lbl.gov/prif-governance> The Committee vote to approve the technical content in this revision began on 2025-11-24 and concluded on 2025-12-08 with unanimous approval. The 7-day Committee comment period for cosmetic feedback began on 2025-12-08 and concluded on 2025-12-15 with no comments. See the Change Log in Section 1 of the document for the list of changes relative to the prior revision.
Flang
Flang is a ground-up implementation of a Fortran front end written in modern C++. It started off as the f18 project (https://github.com/flang-compiler/f18) with an aim to replace the previous flang project (https://github.com/flang-compiler/flang) and address its various deficiencies. F18 was subsequently accepted into the LLVM project and rechristened as Flang.
Please note that flang is not ready yet for production usage.
Getting Started
Read more about flang in the docs directory. Start with the compiler overview.
To better understand Fortran as a language and the specific grammar accepted by flang, read Fortran For C Programmers and flang's specifications of the Fortran grammar and the OpenMP grammar.
Treatment of language extensions is covered in this document.
To understand the compilers handling of intrinsics, see the discussion of intrinsics.
To understand how a flang program communicates with libraries at runtime, see the discussion of runtime descriptors.
If you're interested in contributing to the compiler, read the style guide and also review how flang uses modern C++ features.
If you are interested in writing new documentation, follow LLVM's Markdown style guide.
Consult the Getting Started with Flang for information on building and running flang.