Selection Monad

Jakub Daniel jakub.daniel at
Tue Jan 24 17:23:58 UTC 2017

Hi Eric,

Just to clarify, my question was not about endorsing another library but
rather extending the ones currently maintained by the committee with
definition of a notion closely related to what is already contained in the
libraries. It just so happens that Edward Kmett implemented the notion in a
standalone library. However to me it does not make much sense to include
ContT but not SelT (currently under the name Search) in the core libraries,
despite their connection. I understand if this does not change the answer

Best Regards,
Jakub Daniel

On Tue, 24 Jan 2017 at 17:39 Eric Mertens <emertens at> wrote:

> Hi Jakub,
> The core libraries committee helps maintain libraries that are already
> critical to the Haskell ecosystem. It doesn’t select new libraries to be
> recommended to users. It’s possible that the search package is a hidden gem
> that more people need to know about. To accomplish that people will need to
> write software using it, market it with blog posts, and bring it up in
> discussions.
> Best Regards,
> Eric Mertens
> On Jan 24, 2017, at 5:57 AM, Jakub Daniel <jakub.daniel at> wrote:
> Hello,
> I apologize in case this is not the right place to bring this
> question/proposal up. Some time ago I stumbled upon the Selection Monad [1]
> (also referred to as Search from the search package on hackage). Its
> relation to the Continuation Monad and the usefulness demonstrated in [1]
> made me wonder whether it would be nice to include Selection Monad in the
> core libraries along the Continuation Monad (in mtl and transformers) with
> all the business of selections attaining continuations. I can imagine the
> pattern to be too little recognised to justify such an addition, yet the
> theoretical connection to the Continuation Monad seems to be an interesting
> one and worth being addressed.
> Best,
> Jakub Daniel
> [1] Jules Hedges. *Monad transformers for backtracking search*. In *Proceedings
> of MSFP 2014. *
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