fused-effects-system VS ghc-whole-program-compiler-project

Until some enterprising PhD student comes along and takes a whack at this problem, I debug my programs by: a) using pure functions whenever possible—I am bad at keeping track of imperative execution in my head, and as such pure functions help me avoid the associated mistakes, and what mistakes I do make are more apparent visually; b) using hedgehog or QuickCheck aggressively, so as to verify that the assumptions I’m making are correct; c) when writing imperative/effectful computation, building in logging from the get-go—I am a fused-effects user, so I use the built-in Trace effect as well as fused-effects-profile to yield information about what’s actually being executed.

Another thing you can try is the ghc-wpc project which has an interpreter which supports breakpoints, though you may need to hack little a bit to achieve your goals.

Here the goal is to build a high level, easy to understand model for all GHC backend features. Validations is also required. Once we know the semantics of GHC primops and RTS features then it becomes possible to figure out how to compile Haskell programs to GRIN. I started the GHC-WPC project for this reason. GHC-WPC exports the STG intermediate representation for the whole Haskell program, and I wrote an STG interpreter from scratch in Haskell that can run any Haskell program. (i.e. GHC itself) The STG interpreter is the high level model for the GHC primop and RTS semantics. It implements all these in pure Haskell, it does not depend on GHC RTS at all.

I can easily debug any Haskell program with the external STG interpreter. https://www.youtube.com/watch?v=DkDUEd3pUyM https://github.com/grin-compiler/ghc-whole-program-compiler-project

I haven't gotten my hands dirty yet, but really excited hearing GHC-WPC is going on!

Why didn't you mention GHC-WPC? It is also a backend sample. It exports enough information (STG + linker opts + c bits) to interpret the program or to generate a binary executable via the regular GHC codegen system. https://github.com/grin-compiler/ghc-whole-program-compiler-project

You could use the GHC codegen and RTS via the external STG IR. https://github.com/grin-compiler/ghc-whole-program-compiler-project

Remarks: 1. Strict functional languages can be expressed in STG without overhead, because STG has explicit liftedness control. In a strict language every data is unlifted or unboxed. 2. Supporting all GHC primops is not unrealistic. See the primop implementation in the external STG interpreter source code. Here is the implementation of the threading primops.