Re: [Caml-list] "Type constructor b would escape its scope"

[Gregory Malecha <gmalecha@gmail.com>]

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Thanks. I'm not sure I understand the difference between the two though. Is
there an example showing when they produce different results?

On Sun, Mar 27, 2016 at 6:12 PM, Jacques Garrigue <
garrigue@math.nagoya-u.ac.jp> wrote:

> On 2016/03/28 03:52, Gregory Malecha wrote:
> >
> > Thanks, Leo --
> >
> > This is exactly what I needed to know. I thought that the (type a)
> annotation was forcing the function to be polymorphic. For future
> reference, is there any way to write the annotation (that forces the
> function to be polymorphic) without having to write explicit ‘fun's?
>
> You should either write
>
>   let generic_search_stream : ‘b. int option -> (internal_result, ‘b)
> result_stream = …
>
> or
>
>   let generic_search_stream : type b. int option -> (internal_result, b)
> result_stream = …
>
> where the latter one both requires polymorphism and defines a locally
> abstract type,
> i.e. probably the behavior you expect with (type b).
>
> Jacques
>
>


-- 
gregory malecha

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