2014 Applicative => Monad proposal

Jeremy Shaw jeremy at n-heptane.com
Thu May 23 22:50:40 CEST 2013

Great! I'd loved to see Pointed in there too -- but I have no dreams
of winning that one. :p

Hopefully this will pave the way for a MonadFail in the future, and
other enhancements.

I maintain Happstack, a bunch of related libraries, and a bunch of
code that uses Happstack, etc. So, I am potentially affected by any
breakage -- but that is fine by me.

Sure we have thousands of users now.. but let's fix this before we
have millions!

- jeremy

On Thu, May 23, 2013 at 2:39 PM, David Luposchainsky
<dluposchainsky at googlemail.com> wrote:
> Hello libraries,
> it's on! Time to tackle the Applicative-Monad issue, hopefully once and
> for all. Over the last couple of weeks I've looked through previous
> proposals, asked #haskell about their opinions, and compiled it all into
> one file that sums up what I made of that. It's a bit long for an email
> and uses markdown, so I'll just provide links at the end of this mail
> instead of pasting it in here. In there, the whole thing and how to
> approach it is explained in more detail. Here's an abstract of what it
> the proposal consists of:
> - Don't break compatibility
> - Apply it gently
> - Applicative m => Monad m
> - Applicative into Prelude (and therefore into the Report)
> - (Alternative m, Monad m) => MonadPlus m
> - Promote `join` into the Monad typeclass
> Let's make this happen! I'm going to give a ballpark discussion period
> of four weeks, but since I can imagine this discussion could become
> quite complex we shouldn't take it too serious. I'll summarize what's
> been going on periodically though.
> David
> Links:
> The proposal text on Github (link fixed, sorry for the deadlink yesterday):
> https://github.com/quchen/articles/blob/master/applicative_monad.md
> (This file is subject to changes, depending on how this discussion goes.
> I'll try to make it reflect the current consensus.)
> And just in case Github silentbans me again for submitting too many
> edits to my Gist (grrr), here's a copy of the file on HPaste as backup:
> http://hpaste.org/88423
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