Question on Variant Types - fa.caml

Message from discussion Question on Variant Types

Jonathan Roewen

More options Jun 28 2006, 7:54 pm

Newsgroups: fa.caml

From: "Jonathan Roewen" <jonathan.roe...@gmail.com>

Date: Wed, 28 Jun 2006 23:54:04 UTC

Local: Wed, Jun 28 2006 7:54 pm

Subject: Re: [Caml-list] Question on Variant Types

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> Followup question:
> Given I have:
> type foo = [`A | `B of int | `C of char]
> type bar = [`B of int | `C of char| `D]

> and a function
> let f (x : foo) : bar =
> match x with
> `A -> `D
> |`B _
> |`C _ -> (x : bar)

> Is there any way to properly coerce this using the restricted variant
> information of x? Or do I have to duplicate code and reconstruct x?

let f (x : foo) : bar = match x with
| `A -> `D
| `B _ | `C _ as x -> (x : bar)

Jonathan

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