[zvrba]

This is the author's position: "This essay introduces OpenGL and its pitfalls for the PL-minded reader and advocates for more research that applies language ideas to this underserved domain. "

> He criticizes Metal for using a version of C++14 that doesn't allow recursion, but offers no alternate solutions

No, he criticizes GLSL and HLSL for extending C or C++ in an ad-hoc way which make them buggy and unreliable (myriad of small differences between implementations).

"The need for ad hoc language extension also complicates compiler implementations: current compilers either need to reinvent a complete C-like parser and compiler from scratch [28] or hack an existing frontend such as GCC or Clang. Both approaches are error prone: [...]"