title: Composing functions in Haskell with arithmetic-type functions
body: <p>I'm learning Haskell now and I'm trying to play around with function composition.</p>
  
  <p>I wrote two functions.</p>
  
  <p><code>let func1 x y = x + y</code></p>
  
  <p><code>let func2 t = t*2</code></p>
  
  <p>However, when I try to compose these two functions, 
  <code>func2 . func1 1 2</code> I am expecting to get 6. </p>
  
  <p>Instead, I get this error:</p>
  
  <pre><code>   No instance for (Num (a -&gt; b))
        arising from a use of `func1' at &lt;interactive&gt;:1:8-16
      Possible fix: add an instance declaration for (Num (a -&gt; b))
      In the second argument of `(.)', namely `func1 1 2'
      In the expression: func2 . func1 1 2
      In the definition of `it': it = func2 . func1 1 2
  </code></pre>
  
  <p>Can someone explain why this is not working?</p>