{"slug": "transpiler-from-j-to-fortran", "title": "Transpiler from J to Fortran", "summary": "A developer has created a transpiler from the J programming language to Fortran using OpenAI Sol, enabling batch translation and a REPL that translates and runs Fortran code on the fly. The tool works on small J programs but cannot handle more dynamic programs such as those in the jlearn machine learning library or astronomy programs. Claude Opus suggests a larger subset of J code could be transpiled to Python/Numpy calling Fortran as needed.", "body_md": "[J](https://www.jsoftware.com/#/) is an offshoot of APL, co-authored by Iverson, that uses the ASCII character set. Since modern Fortran is also an array programming language, and since it [has been argued](https://martinalderson.com/posts/which-programming-languages-are-most-token-efficient/) that token-efficient languages such as J are a good fit for LLMs, I wrote a transpiler from J to Fortran using OpenAI Sol primarily\n\nBesides a batch translator there is a REPL that translates and runs Fortran code on the fly. It works on some small J programs, but it cannot handle the more dynamic programs at [GitHub - jonghough/jlearn: Machine Learning Library, written in J · GitHub](https://github.com/jonghough/jlearn) or the programs for astronomy [here](https://pages.astro.umd.edu/~jpha/J_page.html). Claude Opus says that a larger subset of J code could be transpiled to Python/Numpy calling Fortran as needed.", "url": "https://wpnews.pro/news/transpiler-from-j-to-fortran", "canonical_source": "https://fortran-lang.discourse.group/t/transpiler-from-j-to-fortran/11049#post_1", "published_at": "2026-08-15 16:09:52+00:00", "updated_at": "2026-08-15 16:11:56.383598+00:00", "lang": "en", "topics": ["developer-tools", "artificial-intelligence"], "entities": ["OpenAI Sol", "J", "Fortran", "Claude Opus", "jlearn", "GitHub"], "alternates": {"html": "https://wpnews.pro/news/transpiler-from-j-to-fortran", "markdown": "https://wpnews.pro/news/transpiler-from-j-to-fortran.md", "text": "https://wpnews.pro/news/transpiler-from-j-to-fortran.txt", "jsonld": "https://wpnews.pro/news/transpiler-from-j-to-fortran.jsonld"}}