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[Caml-list] References to polymorphic variants
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Date: -- (:)
From: nickgrey@s...
Subject: [Caml-list] References to polymorphic variants
Hi, 

I want to be able to store an arbitrary polymorphic variant in a reference: 

let (x : ([> ] option) ref ) = ref None ;; 

(Not my actual code, I've boiled it down to a minimal example.) 

This won't compile because it "contains a type variable which cannot be 
generalized".  I understand this error message in other contexts.  If my 
code were 

let x = ref None 

then I could break type safety by putting (Some 1) into the reference, and 
later reading the reference with type (string option) thus casting a string 
to an int. 

But as I'm dealing with a polymorphic variant, surely this should not apply. 
My understanding of polymorphic variants is that you do not need to specify 
at the time of declaration what types it might contain. 

So, what am I doing wrong and how can I get around it? 

Regards,
Nick 

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