<div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">From: David Menendez <<a href="mailto:dave@zednenem.com">dave@zednenem.com</a>><br>
Subject: Re: Functor => Pointed => Applicative => Monad<br>
To: Isaac Dupree <<a href="mailto:ml@isaac.cedarswampstudios.org">ml@isaac.cedarswampstudios.org</a>><br>
Cc: <a href="mailto:libraries@haskell.org">libraries@haskell.org</a><br>
Message-ID:<br>
<<a href="mailto:AANLkTinkqQXYTN6ATqGawbdeVvtfq_6z51sADN8i_O8P@mail.gmail.com">AANLkTinkqQXYTN6ATqGawbdeVvtfq_6z51sADN8i_O8P@mail.gmail.com</a>><br>
Content-Type: text/plain; charset=ISO-8859-1<br>
<br>
On Mon, Nov 29, 2010 at 11:26 AM, Isaac Dupree<br>
<<a href="mailto:ml@isaac.cedarswampstudios.org">ml@isaac.cedarswampstudios.org</a>> wrote:<br>
> On 11/29/10 03:39, John Smith wrote:<br>
>><br>
>> Is there any intention to reorganise the standard class hierarchy,<br>
>> arranging them logically instead of in order of invention? I plagiarised<br>
>> the following example from<br>
>> <a href="http://stackoverflow.com/questions/1634911/can-liftm-differ-from-lifta" target="_blank">http://stackoverflow.com/questions/1634911/can-liftm-differ-from-lifta</a><br>
>> and Trac:<br>
>><br>
>> class Functor f where<br>
>> map :: (a -> b) -> f a -> f b<br>
>><br>
>> class Functor f => Pointed f where<br>
>> pure :: a -> f a<br>
><br>
> Is it useful to have Pointed non-Functors?<br>
<br>
Is Pointed useful at all? The last time this discussion came up, I<br>
asked for algorithms which were generic over pointed functors (in the<br>
same way that traverse is generic over applicative functors) and no<br>
one could think of any.<br></blockquote><div><br></div><div>It's useful for 'singleton' on probabilistic data structures (e.g. a Bloom filter).</div><div><br></div><div>John</div></div>