Roelof, please consider changing your mail client to send *both* HTML and plain-text emails! With your current setting you send *only* HTML sometimes and it results in a slightly broken list archive, see [1] for an example of the result. To boot, you also make it more difficult for those of us who use plain-text mail clients to benefit from the diskussions you participate in. /M [1]: https://mail.haskell.org/pipermail/beginners/2015-February/014808.html On Thu, Feb 26, 2015 at 03:01:22PM +0100, Roelof Wobben wrote:
<html> <head> <meta content="text/html; charset=windows-1252" http-equiv="Content-Type"> </head> <body bgcolor="#FFFFFF" text="#000000"> <div class="moz-cite-prefix">Oke, <br> <br> So a leaf is a node which has no "branch"<br> <br> I have made a exercise where I have to made the logMessages. <br> Now I have to turn them into a tree <br> <br> Where does the second entry goes then ?<br> <br> Roelof<br> <br> <br> Konstantine Rybnikov schreef op 26-2-2015 om 14:56:<br> </div> <blockquote cite="mid:CAAbahfQO5o+Db_qy_B+vb3E6WWb1bdeQBmpAPa6E-5TwTjerjg@mail.gmail.com" type="cite"> <div dir="ltr"> <div> <div> <div> <div> <div> <div> <div>Hi Roelof,<br> <br> </div> I think you misunderstood it.<br> <br> </div> <div>There are two things here: types and values (value-constructors). They exist in different world, not touching each other.<br> <br> </div> <div>In Haskell, you define a type as:<br> <br> </div> <div>data <Type_Name> = <ValueConstructor_Name> <Type_Name> <Type_Name> <Type_Name><br> <br> </div> <div>You can create values as:<br> <br> </div> <div>let varName = <ValueConstructor_Name> <Value> <Value> <Value><br> <br> </div> <div>You need to put <Value> of some type, not type name itself in place of those <Value>s.<br> <br> </div> <div>So, with datatype you provided, you have two data-constructors:<br> <br> </div> <div>Leaf<br> <br> </div> <div>and<br> <br> </div> <div>Node <val> <val> <val><br> <br> </div> <div>You can create a leaf:<br> <br> </div> <div>let leaf = Leav<br> <br> </div> <div>or a node:<br> <br> </div> <div>let node = Node Leaf "msg" Leaf<br> <br> </div> <div>You can see that Node is a data-constructor that takes 3 values, not type-names as it's parameters.<br> <br> </div> <div>Hope this helps.<br> </div> </div> </div> </div> </div> </div> </div> <div class="gmail_extra"><br> <div class="gmail_quote">On Thu, Feb 26, 2015 at 3:21 PM, Roelof Wobben <span dir="ltr"><<a moz-do-not-send="true" href="mailto:r.wobben@home.nl" target="_blank">r.wobben@home.nl</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello,<br> <br> Suppose we have this definition of a tree :<br> <br> data MessageTree = Leaf<br> | Node MessageTree LogMessage MessageTree<br> deriving (Show, Eq)<br> <br> let Message = LogMessage "E 1 this is a test error"<br> let Message = LogMessage "e 2 this is the second test error "<br> <br> As I understand it right I can make the first entry like this : first_entry = Node Messagetree Message Messagetree<br> <br> And the second one like this second_entry = Node Message Messagetree Message2 Messagetree ??<br> <br> Roelof<br> <br> _______________________________________________<br> Beginners mailing list<br> <a moz-do-not-send="true" href="mailto:Beginners@haskell.org" target="_blank">Beginners@haskell.org</a><br> <a moz-do-not-send="true" href="http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners" target="_blank">http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners</a><br> </blockquote> </div> <br> </div> <br> <fieldset class="mimeAttachmentHeader"></fieldset> <br> <pre wrap="">_______________________________________________ Beginners mailing list <a class="moz-txt-link-abbreviated" href="mailto:Beginners@haskell.org">Beginners@haskell.org</a> <a class="moz-txt-link-freetext" href="http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners">http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners</a> </pre> </blockquote> <br> </body> </html>
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