[andreypopp]

> What’s wrong with opam?

I'd say the main problem is that local switches and lock files are still not the default mode of operation.

Also opam lacks a global cache of built packages which esy provides (esy's cache is modelled after Nix package manager). So every new opam local switch effectively compiles everything from scratch. Though, as I understand this aspect is going to be addressed by dune at some point (though esy caches not just OCaml built artefacts but also C/C++).

(Full disclosure: I'm biased as I'm one of the original developers of esy)