<div>I suppose having a good description of what I'd like to do might help: I'd like to be able to make an N-Tuple an instance of a type class.</div>
<div> </div>
<div>class Foo a where</div>
<div> ....</div>
<div> </div>
<div>instance Foo (,) where</div>
<div> ....</div>
<div> </div>
<div>instance Foo (,,) where</div>
<div> ....<br></div>
<div>The different kindedness of (,) and (,,) prevent this from working. </div>
<div> </div>
<div>/jve</div>
<div><br> </div>
<div class="gmail_quote">On Mon, Mar 30, 2009 at 2:00 PM, Martijn van Steenbergen <span dir="ltr"><<a href="mailto:martijn@van.steenbergen.nl">martijn@van.steenbergen.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">
<div class="im">John Van Enk wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"> > Haskell not having 'polymorphic kinds'.<br> Is there a good description of why Haskell doesn't have polymorphic kinds?<br>
</blockquote><br></div>IANA expert but polymorphic kinds belong to a set of reasonably new influences (e.g. from dependently typed programming languages and generic programming) and they haven't been 1) polished enough to be a widely accepted standard or 2) simply haven't been implemented yet (low priority, etc).<br>
<br>Besides that, I sometimes see polymorphic kinds in GHC error messages, so I suspect that at least parts of GHC already support them.<br><font color="#888888"><br>Martijn.<br><br></font></blockquote></div><br><br clear="all">
<br>-- <br>/jve<br>