13:18 <discocaml_> <deepspacejohn> The documentation for -rectypes says this "By default, only recursive types where the recursion goes through an object type are supported." https://ocaml.org/manual/5.2/comp.html

13:18 <discocaml_> <deepspacejohn> This an error or does "object type" mean something different than the type of OCaml objects?

13:19 <discocaml_> <deepspacejohn> *is this

13:27 <discocaml_> <octachron> I am not sure that I follow? An object type is a kind of type, like a tuple type or an arrow type.

13:29 <discocaml_> <octachron> For instance, in `val x : < m:int > ` the type of `x` is an object type.

13:33 <companion_cube> Shouldn't the doc of rectypes say "this is for esoteric purposes, do not use"? 🤣

14:19 <discocaml_> <deepspacejohn> `type 'a t = Cons of 'a * 'a t` is recursive and does not go through an object type.

14:20 <discocaml_> <deepspacejohn> so " only recursive types where the recursion goes through an object type are supported" seems incorrect?

14:21 <discocaml_> <._null._> This is equirecursivity, the well-behaved variant. `-rectypes` enables isorecursivity (`< x: 'a> as 'a` for object types)

14:24 <discocaml_> <._null._> I mixed up the two terms, isorecursivity is the always enabled well behaved one

14:27 <discocaml_> <octachron> The type definition in your example is recursive, the type expression itself is not recursive.

14:30 <discocaml_> <octachron> Basically, the definition gives you way to construct or destruct values of type `'a t` that involves `'a t` itself, but it is not stating that parts of the type is equal to the whole type.

14:31 <discocaml_> <deepspacejohn> interesting, that makes more sense now. I hadn't considered the differences between expressions and definitions for that

16:18 <theblatte> seems like opam 2.0 doesn't let you install dependencies of a lock file, eg "opam install --locked --deps-only opam/utop.opam.locked" wants to install packages at the wrong versions

16:20 <theblatte> also is there a way to tell opam not to perform other actions than the one I asked? "opam remove utop" wants to recompile a bunch of stuff due to upstream changes in addition to removing utop

16:33 <rustyne> theblatte: --criteria="-changed" helps?

16:33 <rustyne> without going into the runes of https://opam.ocaml.org/doc/External_solvers.html

16:35 <rustyne> (I’m not sure rebuilding counts as changing)

16:39 <theblatte> rustyne: nope

16:40 <theblatte> actually some of these packages use utop some it's ok that they are recompiled, my bad

17:57 <discocaml_> <deepspacejohn> @._null._ is there any documentation/literature about the different kinds of recursion? "isorecursive" has 0 results on google

17:58 <discocaml_> <deepspacejohn> actually never mind, it has results but I searched "isorecursivity" first which had 0.

17:59 <discocaml_> <andreypopp> TAPL discusses this

18:01 <discocaml_> <deepspacejohn> cool, thanks for the pointer