LLVM
1 HN recommender · recommended in 7 months, 2018–2023
26:01 · 61K views · Nov 14, 2018
Christian Schafmeister presents lessons from six years of implementing Clasp, a Common Lisp compiler using LLVM as its backend that interoperates with C++. He explains handling a dynamic, memory-managed language on LLVM.
Mostly cited by the author himself as the introduction to Clasp and Cando, and recommended to those wanting Lisp with C++ library interop.
8 comments from Hacker News
While it's nowhere near as mature as Racket, those interested in this use case might also be interested in Clasp, a Common Lisp implementation built on LLVM specifically to enable the combination of Lisp-style dynamic development approaches with C++ libraries. [LINK] this video
My group is developing Clasp (github.com/clasp-developers/clasp.git). It's a Common Lisp implementation that interoperates with C++ and uses llvm as the backend. It's something you might want to look at because it could change your options in the following ways: (1) Clasp interoperates with C++ - C++ libraries like graphics and physics engines can be easily exposed within Clasp Common Lisp. (See [LINK] ) (2) Clasp uses llvm as the backend - it generates llvm-ir from Common Lisp code and uses link time optimization to link C++ and Common Lisp generated llvm-ir. (3) Clasp uses the Memory Pool System garbage collector, which can be configured to minimize GC pause times to a programmer-defined level. (4) Clasp generates debug info and can be profiled with standard tools like dtrace and C++ functions, Common Lisp functions and GC functions are all profiled against each other. I'm a professor of Chemistry at Temple University - I'm developing Clasp to design molecules and materials - but it could be applied to a lot of other problems. Caveat: Clasp is not yet as performant as Steel Bank Common Lisp, but it uses the open source and highly configurable Cleavir compiler developed by Robert Strandh and we have incorporated inlining and are currently incorporating type inference. If you want to see a little bit more - I have a 25 min talk up on youtube that I presented a couple of weeks ago at the 2018 llvm developers meeting ( this video )
A growing group of us are implementing Clasp ( [LINK] ) - a new Common Lisp that uses Robert Strandh's Cleavir compiler, interoperates with C++ and uses LLVM as the backend. Clasp is the foundation of Cando - a programming environment for the development of molecular devices ( this video ). Robert Strandh is an exceptionally clear thinker and a fantastic programmer. I can't count the times that Robert has implemented changes to the Cleavir compiler source code and without him being able to test it (long story) passed it to me and it ran flawlessly in Clasp. I implemented his fast generic function solution within Clasp based on another of his papers ( [LINK] ). Edit: Basically - if Robert writes it up in a paper - I want to have the implementation. Once we develop molecular robots - they are going to implement LispOS. :-)
Counterpoint - I implemented a Common Lisp compiler that uses llvm as the back end ( [LINK] ). I've kept up with the versions from 3.6 to 6.0 and I'm about to upgrade to 7.0. I'm not sure why other projects find this difficult but I have noticed that if I get too far behind it does get a bit more difficult. I exposed the C++ API to Common Lisp and write all of the compiler in Common Lisp. The Clang C++ compiler tells me what is broken when I upgrade to a new version of llvm and then I fix it. I talk about it here this video at about 13:30
More presentations! I think two are almost the same presentation: [LINK] (July 2010) 10S6P4 Christian Schafmeister 2010 UNTT 3rd Annual Conference Session 6 Presentation 4 [LINK] (July 2015) Clasp: Common Lisp using LLVM and C++ for Molecular Metaprogramming [LINK] (Aug 2015) Clasp: Common Lisp using LLVM and C++ for Designing Molecules [LINK] (Oct 2018) Modular Polymer Catalysts - Chris Schafmeister this video (Nov 2018) LLVM Developers Meeting: C. Schafmeister lessons Learned Implementing Common Lisp with LLVM