Comment by norir

I know from experience that this initial assumption is wrong. Compiler performance is dominated by algorithms. The fastes managed languages tend to be at worst within a factor of two for wall time on any given algorithm. Algorithmic differences can be unbounded in their performance gaps. Zig itself is a perfect counterexample to the theory that writing a compiler in a low level systems language will lead to a fast compiler. Roc seems to compile at around 15k lines per second. That is not fast. There were evidently compilers written in ml that did 3k likes per second in 1998 https://flint.cs.yale.edu/cs421/case-for-ml.html

The zig rewrite of roc looks like the author's second compiler. Compiler and language design is a skill like any other and from my vantage point, they appear to have overcommitted to an initial design at the expense of developing their higher level design skills. In my opinion, the best thing they could do for the future of roc is stop working on their current compiler and use it to write a self hosting compiler for a much smaller subset of roc. They should be able to do that in less than 10k lines of code. They might even find that their self hosting compiler is faster than their zig based bootstrap compiler for the self hosted subset of roc. If the self hosting compiler is inadequate. Now they at least have identified a smaller useful subset of roc and can experiment with different compiler implementations in 10k likes of code rather than 300k lines of code. Then they could actually test the theory of whether or not a low level language is necessary to meet whatever arbitrary compiler performance goals they have.

By self hosting, they would also discover what roc features actually matter and they would spend much more time actually writing roc code. The features that are needed to write a self hosted compiler are all features that are generally useful. By improving the self hosted compiler, they also improve downstream programs.