Hi,<div><br></div><div>Please reply to the list so others can contribute.<br><br><div class="gmail_quote">On 11 March 2012 14:42, bahadýr altan <span dir="ltr">&lt;<a href="mailto:doaltan@yahoo.co.uk">doaltan@yahoo.co.uk</a>&gt;</span> wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="font-size:12pt;font-family:times new roman,new york,times,serif"><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">

I&#39;m sorry if I mislead you, I think I didn&#39;t mention my problem clearly there. I&#39;m actually stuck in the position of declaring subtrees, I couldn&#39;t find a solution to that.</div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">

<br></div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">My function is like</div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">

<br></div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">f :: Tree -&gt; Tree</div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">

<br></div><div>And my tree structure is like </div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt"><br></div><div>data Tree = Empty | Branch Integer Tree Tree <br></div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">

<br></div><div style="font-family:&#39;times new roman&#39;,&#39;new york&#39;,times,serif;font-size:12pt">And When I write this which I learned from you : </div><div>(c1, c2, d1, d2, e1, e2 :: Tree)<br></div><div><br></div>

<div>I get error. If you tell me How should I solve that I&#39;d appreciate.</div></div></div></blockquote><div><br></div></div>Hence I was suggesting to think about the types of the pattern variables.
</div><div><br></div><div><font face="&#39;courier new&#39;, monospace">f (Branch x (Branch y y1 y2) (Branch z z1 z2)) = (x,y,y1,y2,z,z1,z2)</font></div><div><br></div><div>This definition will work, and return a 7-tuple given a Tree. Try to load this into ghci and see what the type of f is (:t f).</div>

<div>One hint: y and y1 aren&#39;t of the same type.</div><div><br></div><div>Ozgur</div><div><br></div>