[Caml-list] problem to use gadt

[Nicolas Boulay <nicolas@boulay.name>]

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I try to define my own type system using gadt. But it seems that is complex
to mix both type system : mine and the ocaml one.

This tiny example did not compile:

type _ t =
 | Or: _ t * _ t -> _ t
 | Int : int t
 | Float : float t

let a = Or (Int, Float)  (*is ok*)

let (||)  a b = Or (a, b)

let aa = Int || Float (*Error: '_a t, contains type variable that cannot be
generalized*)

Using an operator make a difference. But how to exprime "don't care" if a
choice between 2 types is not possible to be define.  It could be nice if
"('a | 'b) t" worked :) Should i use normal sum type, and make all type
check by a function ?

Nicolas Boulay

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