That could definitely work if all the fields could be specified beforehand.. <div>There are some situations where I won&#39;t know which field (out of many) will be needed to use, and they will change often, </div><div>but I think I can finalize the superset of all-possible fields to be used,</div>
<div>and set up a &quot;master&quot; record for them..  I&#39;m working on music, so the parameters/fields change often and are used in many different combinations.</div><div>I&#39;m working on an Algorithmic Composition environment where the basic functionality is written in Ruby, and the meta-level composition/performance instructions are controlled from Haskell..</div>
<div>It seeming to be a great combination !</div><div><br></div><div>Thanks so much for the help, I&#39;ll be posting questions in the Haskell Cafe from now on, but will still be monitoring this list.</div><div><br></div>
<div>Cheers,</div><div><br></div><div>Tom</div><div><br></div><div><br></div><div><br><div class="gmail_quote">On Wed, May 26, 2010 at 5:50 PM, Philip Weaver <span dir="ltr">&lt;<a href="mailto:philip.weaver@gmail.com">philip.weaver@gmail.com</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">(in gmail, I just use reply all).<div><br></div><div>Yeah, that&#39;s certainly a valid solution, but ugly like you said.</div>
<div><br></div><div>Would a record like this work better for you?</div><div><br></div><div><font face="&#39;courier new&#39;, monospace">data Foo = { root :: Root, oct :: Oct, mode :: Mode }</font></div>

<div><br></div><div>It accomplishes the same thing.  Each field can have at most one value, you can update any field, and you can leave any fields uninitialized like this:</div><div><br></div><div><font face="&#39;courier new&#39;, monospace">initFoo = Foo { root = error &quot;root is not initialized&quot;,</font></div>


<div><font face="&#39;courier new&#39;, monospace">                oct  = error &quot;oct is not initialized&quot;,</font></div><div><font face="&#39;courier new&#39;, monospace">                mode = error &quot;mode is not initialized&quot;</font></div>


<div><font face="&#39;courier new&#39;, monospace">              }</font></div><div><font face="&#39;courier new&#39;, monospace"><br></font></div><div><div class="gmail_quote"><div><div></div><div class="h5">

On Wed, May 26, 2010 at 1:35 PM, Tom Jordan <span dir="ltr">&lt;<a href="mailto:viresh53@gmail.com" target="_blank">viresh53@gmail.com</a>&gt;</span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div></div><div class="h5">

Sorry that I couldn&#39;t respond to the previous thread.. I&#39;m using Gmail and not an email client so I couldn&#39;t use the reply button. I&#39;ll try to resolve this issue soon !<div><br><div>Thanks Phillip for responding so quickly,</div>



<div><br></div><div>I tried Data.Map first and ran into the issue you mentioned..</div><div><br></div><div>I&#39;ve found a way to get around it, but it&#39;s ugly and verbose..</div><div><br></div><div>Instead, I&#39;m wondering if there is a way to use the constructors for the &quot;Val&quot; types below, in place of the keys such as:</div>



<div><br></div><div>data Val = Root Root | Oct Oct | Mode Mode deriving (Show, Eq, Ord)</div><div><br></div><div>And matching against the constructors, instead of resorting to this:</div><div><br></div><div><br></div><div>



<div>import IO</div><div>import qualified Data.Map as Map</div><div><br></div><div>type Root = String</div><div>type Oct  = Integer</div><div>type Mode = Integer</div><div><br></div><div>data Key = Root | Oct | Mode deriving (Show, Eq, Ord)</div>



<div>data Val = Root_v Root | Oct_v Oct | Mode_v Mode deriving (Show, Eq, Ord)</div><div><br></div><div>test = Map.insert Oct (Oct_v 3) . Map.insert Mode (Mode_v 0) . Map.insert Root (Root_v &quot;2&quot;) $ Map.empty</div>



<div><br></div><div>main = print test</div><div><br></div><div>--  ----&gt;  fromList [(Root,Root_v &quot;2&quot;),(Oct,Oct_v 3),(Mode,Mode_v 0)]</div><div><br></div><div><br></div><div>Many Thanks,</div><div><br></div><font color="#888888"><div>



Tom</div></font></div></div>
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