Hi, I'm an Outreachy applicant. Could this be my first contribution?

Hi @nobrowser: yes it could, but I think that writing documentation on this point requires a good familiarity with the OCaml type system (it's a newcomer job because it does not require familiarity with the compiler implementation). If you are not familiar with GADTs or the behavior of the example given above, I would maybe recommend picking an easier task.

Hmm. Has someone uttered my name? That is not an action one should take lightly! AAAARRRRGGHHHHH!

Indeed, I meant @notemaster; sorry @nobrowser :-)

Okay, I did spend a bit of time familiarizing myself with certain examples of GADT's and I have some background in Type theory but I'm not super solid on everything thats going here. I'll look at another job then but keep this one on the backburner. Thanks @gasche!

I have moved the issue to the advanced section of newcomer-jobs because it is the true that it requires a very specific skill set for a newcomer.

If I understand this correctly, this behavior is because in the first case the type is assumed to be non-injective, thus it unifies int t s and float t s whereas in the second case, the type is injective, thus int t s and float t s are now distinct and can be refuted. (Apologies for the imprecise wording, I guess, not too well-versed with OCaml's type theory)

Note: there is now a proposed PR, #9500, that introduces explicit annotations for injective type parameters (type !'a t= ...). It comes with minimal changes to the manual (see the current diff) that may interact with the request in this issue. Note that the new documentation is in the "type declaration" part of the reference manual, there would probably remain to mention injectivity explicitly in the GADT chapter.

This issue has been open one year with no activity. Consequently, it is being marked with the "stale" label. What this means is that the issue will be automatically closed in 30 days unless more comments are added or the "stale" label is removed. Comments that provide new information on the issue are especially welcome: is it still reproducible? did it appear in other contexts? how critical is it? etc.

This issue has been open one year with no activity. Consequently, it is being marked with the "stale" label. What this means is that the issue will be automatically closed in 30 days unless more comments are added or the "stale" label is removed. Comments that provide new information on the issue are especially welcome: is it still reproducible? did it appear in other contexts? how critical is it? etc.