[certik]

Yes, that's one answer. But I actually think you can absolutely have both in the same compiler. But you need to have two backends, as I described. You use the custom backend for development (fast to compile) and you use LLVM for release (fast to run).

[fc417fc802]

Well yes, but at that point aren't you effectively writing two compilers in one? It seems to me that would be at odds with wanting it to be fast to compile itself (you said under 30s) and would make it more difficult for the uninitiated to contribute to.

I don't mean to discourage and I don't disagree with the aims. I just have the (possibly mistaken) impression that compilers inevitably fall on a continuum from simple and fast to complex and slow.

[certik]

No, you "only" have to write a backend. Which is still a lot of work, but much less work than another compiler. There are multiple ways it can be designed, but one idea that I like the most right now is to create an API for LLVM, and then implement the same API ourselves with a fast backend. That way we reuse everything in current LFortran, including lowering to LLVM, we just have to refactor it to use our own API instead.

[nritchie]

A fast-to-compile but slow-to-run LLVM alternative would make Julia much more useable day-to-day too.