Returning to Haskell/Scala: one must also note that these languages require adopting intuitions and patterns that have failed to win controlling mindshare in the “marketplace” of programmer interest. Both languages also rely on differing, but still “heavy” underlying runtimes.

And while Koka/Eff model a more imperative code-style, they are still highly abstracted from the implementation details of the underlying systems they run on (Koka’s perseus memory allocation scheme notwithstanding). Rust strikes a nice balance with memory safety, strictness and fine-grained memory.

Yet Koka/Eff are research languages, pioneered by academics to explore ideas & expand human knowledge. RStrong seeks to be a language that brings these concepts into “industrial” use. As in: suitable for a range of software across disparate domains. This means addressing modularity & other concerns.

“Effective” programming languages already exist: Koka, Eff in addition to the above-mentioned Haskell & Scala. But strictly-typed, “purity aware” functional languages exist on an extreme end of a spectrum, where on the opposite end, languages model how computing systems actually work (e.g. C, Rust)