Re: [boost] Monad (was: Re: [Boost-users] [afio] Formal review of Boost.AFIO)

Subject: Re: [boost] Monad (was: Re: [Boost-users] [afio] Formal review of Boost.AFIO)
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2015-08-25 08:25:19

On 25 Aug 2015 at 0:30, Sam Kellett wrote:

> > Monad has all those items you mention. See
> > https://ned14.github.io/boost.monad/singletonboost_1_1monad_1_1basic__
> > monad.html under the section "Functional programming extensions
> > (optional)".
> >
> > You also get to customise them to your heart's content via the policy
> > class infrastructure. After all, basic_future<> which subclasses
> > basic_monad<> implements binds as continuations.
> 
> that does look good, don't get me wrong. but would i be able to use it to,
> say, provide monadic options to std::list? or io ala haskell? because if
> not i would wonder why not simply because it's called 'monad'.
> 
> what if i wanted to use the >> operator on a boost::optional, could i do
> that with your monad type?

Monad only provides monadic operations to monad<T>. So 
monad<std::list<T>> works as expected, and it is very cheap (often 
completely zero cost) to wrap any type U into monad<U>.

> i'm sure i'm being dense, but i couldn't find an example of the policy
> infrastructure so i couldn't answer those questions myself.

Documenting all that would take at least three months. Hence why 
Monad is not ready for review.

Niall

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