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Translate Fortran to C++ with AI and RAG
- nevi-me 1y agoMicrosoft demoed a version of their GraphRAG that translated C code to (I believe) mostly idiomatic Rust, and it ran without errors. I tried to find reference to how they did it, does anyone know? It sounds like this approach of translating old code could help speed up teams that are looking at rewrites. I also have some old code that's in Kotlin that I'd like to move to something else. I had a bad NullPointerException take down my application after missing a breaking change in a Kotlin update.
- npalli 1y ago[flagged]
- vlovich123 1y agoOr he’s just mentioning the other major transpiler he’s heard of recently that happens to be C to Rust and wondering how it works and if it could be adapted to other language pairs. You’re the one that’s taken the conversation in a super weird direction all by your lonesome.
- nevi-me 1y agoI mentioned neither of the things you're shouting at me about. > I also have some old code that's in Kotlin that I'd like to move to something else. Something else was left unmentioned because I'm not even talking about Rust. My reference to it was that I've seen the approach before where a RAG is used to aid in translating C code, and it's an interesting thing which with more examples, might be easier to non-experts like me. Translating languages is of great interest to various communities. I have friends stuck with a Scala codebase written by geniuses who are no longer around, and they want to move it to something else that the team is comfortable with.
- npalli 1y agoMy bad. Sorry. Didn't read the full comment and you didn't deserve the accusations from me.
- vlovich123 1y agoFrom the looks of [1] they have a graph DB storing the code structure and acting as the RAG for an LLM. [1] https://microsoft.github.io/graphrag/ https://microsoft.github.io/graphrag/
- vrighter 1y agoI do not believe it ran without errors on all cases.
- reve893 1y agoIn my experience such methods work really well for small/simple code snippets. Attempting large code snippets is not functional.
- npalli 1y agoThis is great effort, wonder how it compares to Fortran2Cpp https://github.com/HPC-Fortran2CPP/Fortran2Cpp https://github.com/HPC-Fortran2CPP/Fortran2Cpp
- jedimastert 1y agoI'm trying to think of a reason this couldn't be done more directly with a pretty run-of-the-mill transpiler. Like I understand if this is a technical demo and there is a LOT of Fortran code, but...? I've actually had to do this with a couple of different Fortran projects when I was in college, I translated them to C for various reasons. Maybe it's because it was specifically code written by scientists (i.e somewhat brute force and very straightforward) but there really wasn't very many features that I can recall that didn't have a direct C counterpart, other than column major ordering and arrays staring at 1. Was I just blissfully unaware?
- AndrewGaspar 1y agoWhat you want isn't really "output C++ code that is pedantically equivalent to this Fortran code but with the array indexing fixed up", it's usually more like "translate this Fortran module into something that I can offload to a GPU using CUDA/ROCm/etc. with the same high level semantics, but GPU-friendly low level optimizations", and the exact composition of those low level bits probably don't look exactly like a loop-by-loop translation.
- SanjayMehta 1y agoI don’t know what the transpiled code would look like vs that rendered by an LLM, but maybe the hope is that latter will be more readable?
- almostgotcaught 1y agoWhat is the point of this? Fortran is both faster than cpp and easier to write than cpp. It's also by no means a dead or dying or whatever language. Smells like literally "your scientists were so busy they forgot to ask why".
- mkoubaa 1y agoThis. If someone can't correctly articulate the advantages of Fortran they shouldn't be migrating away from it. This is not to say that migrations should never happen.
- greenavocado 1y agoChesterton's Fence
- jeffbee 1y agoI wonder if they feel that the toolchains are just rotting.
- almostgotcaught 1y agoBut they're not https://github.com/flang-compiler/flang https://github.com/flang-compiler/flang https://flang.llvm.org/docs/ https://flang.llvm.org/docs/
- xvilka 1y agoUnlike C++, they even got their standard package manager - fpm[1]. [1] https://fpm.fortran-lang.org/ https://fpm.fortran-lang.org/
- pjmlp 1y agoIt is as standard as vcpkg and conan. ISO Fortran does not acknowledge the existences of FPM, just like any programming language ISO standard, the ecosystem is not part of the standard.
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- pankajdoharey 1y agoLLM as translators for Cobol code to Java or Go should be attempted. And Shut down the IBM mainframe rent seek business for good permanently.
- pjmlp 1y agoThere are COBOL compilers that target JVM and .NET for as long as these technologies exist. There are also modern compilers to IBM mainframes, including Go, C++, Java, PHP,.. Also outside DevOps and CNCF application space very few people bother with Go, specially not the kind of customers that buy IBM mainframes.
- jabl 1y agoThe soon to be GCC 15 release will contain a COBOL frontend. Also other non mainframe compilers have existed for a long time, both proprietary and FOSS. Thus, availability of a compiler is but a small piece of the puzzle. The real problem is the spider web of dependencies on the mainframe environment, as the enterprises business processes have been intertwined into the mainframe system over decades.
- pankajdoharey 1y agoWhich is why i think cross compiling to other dependencies and porting to other languages is a better solution. Many of these dependencies could be hardware specific. As long as core business solutions could be ported would be a win for everyone stuck in decades of vendor lockin.
- alexchamberlain 1y agoI think the point was you could do that in COBOL; the vendor lock in won't go away just because you change language- it goes away when you decide to refactor the code to vendor agnostic solutions.
- pankajdoharey 1y agoYou're absolutely right that switching languages alone doesn't solve the problem. The real issue isn't COBOL itself but the deep entanglement of business logic with the mainframe ecosystem, things like CICS, IMS, and even the way data is stored and processed. But I still think there's a path forward, and I’ll share a thought experiment based on my experience working alongside colleagues who’ve spent years maintaining these systems. I’ve seen firsthand how much frustration COBOL can cause. Many of my colleagues didn’t enjoy writing it, they stuck with it because it paid well, not because they loved the work. The language itself isn’t the hard part; it’s the decades of accumulated technical debt and the sheer complexity of the environment. Over time, these systems become so intertwined with business processes that untangling them feels impossible. But what if we approached it incrementally? Imagine taking an existing COBOL codebase, say, for a large insurance system and identifying the core business logic buried within it. These are the rules and conditions that power critical operations, like calculating premiums or processing claims. Now, instead of trying to rewrite everything at once, you build a parallel backend in a modern language like Java or Go. You don’t aim for a literal translation of the COBOL code, you focus on replicating the functionality in a way that makes sense in a modern context. For example, replace hardcoded file operations with database calls, or screen based interactions with REST APIs. Most mainframe customers already use middleware like MuleSoft or IBM Z/OS Connect to route requests to both systems simultaneously. For every write operation, you update both the mainframe’s DB2 database and a modern relational database like Postgres. For every read operation, you compare the results from both systems. If there’s a discrepancy, you flag it for investigation. Over time, as you handle more and more business scenarios, you’d start covering all the edge cases. This dual system approach lets you validate the new backend without risking critical operations. Of course, this process isn’t without its struggles. Testing is a huge challenge because mainframe systems often rely on implicit behaviors that aren’t documented anywhere. My colleagues used to joke that the only way to understand some parts of the system was to run it and see what happened. That’s why rigorous testing and monitoring are essential you need to catch discrepancies early before they cause problems. There’s also the cultural side of things. People get attached to their mainframes, especially when they’ve been running reliably for decades. Convincing stakeholders to invest in a multi year migration effort requires strong leadership and a clear case for ROI. But I think the effort is worth it. Moving off the mainframe isn’t just about saving money though that’s a big part of it. It’s about future proofing your organization. Mainframes are great at what they do, but they’re also a bottleneck when it comes to innovation. Want to integrate with a third party service? Good luck. Need to hire new developers? Most of them have never touched COBOL. By transitioning to a modern platform, you open up opportunities to innovate faster, integrate with other systems more easily, and attract talent who can actually work on your codebase. In the end, this isn’t a quick fix it’s a long term strategy. But I believe it’s achievable if you take it step by step. Start small, validate constantly, and gradually build up to a full replacement. What do others think? Are there better ways to tackle this problem, or am I missing something obvious?
- musicale 1y agoGood idea. I'd much rather write do concurrent (i = 1:n) y(i) = y(i) + a*x(i) enddo and then let the a compiler translate it into std::transform(par, x, x+n, y, y, [=](float x, float y){ return y + a*x; } ); if C++ is required for some reason.
- WalterBright 1y agoA member of our community accidentally discovered that the D compiler could translate C code to D code. D has a module system, where you import a module and it pulls the global declarations out of it. To speed up this process, there's a compiler switch to output just the global declarations to another file, a .di file, that functions much like a .h file in C. Then there came along ImportC, where a C lexer/parser was welded onto the D compiler logic. aaaand it wasn't long before the switch was thrown to generate a .di file, and voila, the C code got translated to D! This resulted in making it dramatically easier to use existing C headers and source files with D.
- jll29 1y agoAs a slight tangent, a re-write in another language is also an opportunity for the human engineer to re-design parts of the software that was clunky before or so that in the new target language idioms can be used. Using automatic tools - whether AI-based or transpilers - leaves that opportunity unused, and both approaches are likely to create some additional technical debt (errors in translation, odd, non-idiomatic ways of doing things introduced by the automatism etc.).
- Surac 1y agothere is no place for AI or C++ in this game. Just use a Fortran to C Transpiler . But i get it anything AI sounds modern and C++ because of reasons
- hulitu 1y ago> Translate Fortran to C++ with AI and RAG f2c ? But yeah, 1 level of abstraction sucks. We need around 10 to be satisfied.
- cpgxiii 1y agof2c produces pretty sketchy C code. It's very easy for reasonable thread-safe Fortran code to go through f2c and end up as C code with globals and other thread-unsafe constructs. You have to be prepared to completely rewrite the generated C code to make it usable, possibly more unpleasantly than just doing the port by hand.
- deleted 1y ago[deleted]