[Caml-list] Sharing the code between Monad and MonadState?

[Caml-list] Sharing the code between Monad and MonadState?

[bob zhang]

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Hi List,
   Given the syntax of first class module is improved a lot. I try to
encode Monad and MonadState,  http://ideone.com/HgG4M
Unfortunately I found it's still impossible to share the code between
differrent Monad Instances. Is it theoretically impossible or I missed
something?
   Many thanks

-- 
-- Bob

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Re: [Caml-list] Sharing the code between Monad and MonadState?

[Arnaud Spiwack]

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I fail to see why you would use first class modules for that. What you are
"really" trying to use are just functors. Granted the syntax for functors
is awful. But if you are not willing to bear with it, then you would expect
to have some boilerplate. That said, your types monad and monad_state are
the types of a particular monad and a particular state monad (which have
certain initiality property). There is no reason for them to be related,
which may also be the cause of code duplication.


Arnaud Spiwack


On 23 June 2012 16:32, bob zhang <bobzhang1988@gmail.com> wrote:

> Hi List,
>    Given the syntax of first class module is improved a lot. I try to
> encode Monad and MonadState,  http://ideone.com/HgG4M
> Unfortunately I found it's still impossible to share the code between
> differrent Monad Instances. Is it theoretically impossible or I missed
> something?
>    Many thanks
>
> --
> -- Bob
>

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