Re: [Caml-list] concept style using first-class module

[Satoshi Ogasawara <ogasawara@itpl.co.jp>]

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Thank you for the very quick answer.

On 2011/04/13, at 14:27, Jacques Garrigue wrote:
> Unfortunately, you gave yourself the answer: one would need higher
> kinded type variables to do that (they have them in Haskell).
> Namely, in order to use M.t in the result, you need to bind it somewhere,
> but a first-class module type cannot bind a type, and (type s) only works
> with parameterless types.

I understand it.

> So you have to use a real functor here:
> 
> module Foo(M:MonadPlus) = struct
>  let foo m = M.bind m (fun x -> M.return x)
> end
> 
> You can also wrap this functor in a first-class module, but I don't see
> how it would help.

By chance, I have just noticed a functor becomes first-class yesterday.
I'll try this way.

Thanks,
  ogasawara
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