Re: [Caml-list] Newbie comment on constructor syntax

[Alain Frisch <alain.frisch@lexifi.com>]

On 09/11/2015 22:11, Gabriel Scherer wrote:
> Yes, it is already problematic, and in fact I'm personally not
> completely convinced by this feature -- Alain it "reduces bad
> surprises for beginners", but I suspect that adding more magic in this
> place could not actually help that much -- at least the current
> semantic model is simple.

Just to illustrate that the confusion related to n-ary constructors is real:

http://stackoverflow.com/questions/3940345/defining-exceptions-with-tuple-as-argument
http://stackoverflow.com/questions/10306733/ocaml-constructor-unpacking
http://stackoverflow.com/questions/9774671/using-a-variant-type-constructor-with-just-one-tuple-value
http://stackoverflow.com/questions/14818866/int-int-vs-int-int-in-ocaml-sum-type


Now, it's not completely clear that the current proposal is enough to 
reduce significantly the confusion; one could argue that by hiding the 
difference between n-ary constructors and constructors with tuple 
arguments at the value level, one makes it harder for beginners to get 
the right mental model required to understand type inclusion ("type s = 
int * int;; type t = A of s" vs "type t = A of int * int").


-- Alain