]Caml-list] Types

]Caml-list] Types

[Jonathan Roewen]

Hi,

Is it possible to create a record type that has a member which is a
polymorphic type?

I tried: type rect = { mutable x1: 'a; ... } but that doesn't work.
Also, type a = A of 'a doesn't seem to work either.

Jon

Re: [Caml-list] ]Caml-list] Types

[Michael Wohlwend]

On Sunday 19 June 2005 08:42, Jonathan Roewen wrote:
> Hi,
>
> Is it possible to create a record type that has a member which is a
> polymorphic type?
>
> I tried: type rect = { mutable x1: 'a; ... } but that doesn't work.
> Also, type a = A of 'a doesn't seem to work either.

how about:
type 'a rect = { mutable x1:'a }

cheers
 Michael

Re: [Caml-list] ]Caml-list] Types

[Eric Cooper]

On Sun, Jun 19, 2005 at 06:42:01PM +1200, Jonathan Roewen wrote:
> Is it possible to create a record type that has a member which is a
> polymorphic type?
> 
> I tried: type rect = { mutable x1: 'a; ... } but that doesn't work.
> Also, type a = A of 'a doesn't seem to work either.

type t = { f : 'a . 'a -> 'a list }

let x = { f = fun x -> [x] }

let y = { f = fun x -> [x;x] }

-- 
Eric Cooper             e c c @ c m u . e d u

Re: [Caml-list] ]Caml-list] Types

[padiolea]

> On Sun, Jun 19, 2005 at 06:42:01PM +1200, Jonathan Roewen wrote:
>> Is it possible to create a record type that has a member which is a
>> polymorphic type?
>>
>> I tried: type rect = { mutable x1: 'a; ... } but that doesn't work.
>> Also, type a = A of 'a doesn't seem to work either.
>
> type t = { f : 'a . 'a -> 'a list }
>
> let x = { f = fun x -> [x] }
>
> let y = { f = fun x -> [x;x] }


why not simply
type 'a rect = { mutable x1 = 'a; .... }


>
> --
> Eric Cooper             e c c @ c m u . e d u
>
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