Pexp_newtype vs. Pexp_function (in OCaml 5.2.0) ?

[chetmurthy]

In OCaml 5.1.0, there were three different constructors for functions:

1. Pexp_function -- for "function p1 -> e1 | p2 -> e2 | etc"
2. Pexp_fun -- for "fun p1 -> e1"
3. Pexp_newtype -- for "fun (type t) -> e"

With OCaml 5.2.0, all three are unified into Pexp_function, but Pexp_newtype still exists. Is there a reason for this I'm not seeing? The specific reason I ask, is that if you're doing something like ppx_metaquot, the fact that there are two different ASTs for what is actually the same surface syntax -- two entirely different AST constructors -- would seem to make it difficult to implement a metaquot facility.