Re: [Caml-list] Equality between abstract type definitions

[Andreas Rossberg <rossberg@mpi-sws.org>]

On Oct 25, 2013, at 22:32 , Yaron Minsky <yminsky@janestreet.com> wrote:
> Changing the semantics of this will, I think, break a _lot_ of code.

Interesting. Do you have specific examples in mind?

> For what it's worth, I suspect that most people who are surprised by
> this are people who were trained on Standard ML.  At Jane Street we've
> had a lot of people learn the language, and the complaints I've heard
> about this feature are, I think, mostly from that group.

Maybe, but it's not my impression that this is true for most people I see asking related questions here on the list or on SO.

> I also don't find Andreas suggestion particularly intuitive.  I would
> have guessed that (x: '_a) would constrain x to be a weakly
> polymorphic value, which is at odds with the proposal.

Now, _that_ is something I would only expect from programmers trained on SML -- ancient SML'90 to be precise. ;)

Note how OCaml already uses '_a for a sort of flexible variable in its output.

/Andreas