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POUsing map to replace elements of a list with (x-y)*(x-y), where y is the initial element
 

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    <p>I have a bit of homework to do and I am a complete newbie to Haskell. The question I am having trouble with is to write a function which when given an integer <code>x</code> and a list of integers apply <code>(x-y)*(x-y)</code> to each element in the list and output the new list, with <code>y</code> being each element of the input list.</p> <p>I have a very rough idea I will have to use the <code>map</code> function but I'm unsure how to go about it. </p> <p>I have been looking at examples for squaring each element in a list and kind of understand how that works, but how I would implement the <code>(x-y)*(x-y)</code> with <code>y</code> being the current element completely baffles me. </p> <pre><code>squares :: [Int] -&gt; [Int] squares (x:xs) = x * x : squares xs squares [] = [] </code></pre> <p>the exact question I have been set is, </p> <blockquote> <p>Write a function <code>rela</code> which takes as arguments an integer <code>x</code> and a list of integers. It returns a similar list, but where each element <code>y</code> has been replaced by <code>(x-y)*(x-y)</code>, e.g.</p> <pre><code>Main&gt; rela 2 [3,5,7] [1,9,25] </code></pre> </blockquote> <hr> <p>I have managed to get it working after reading through some books, but the code I have made misses out the first element in the list. Any explanation why?</p> <pre><code>equation1 :: Int -&gt; Int -&gt; Int equation1 x y = (x-y)*(x-y) rela :: Int -&gt; [Int] -&gt; [Int] rela x [] =[] rela x (y:ys) = [ equation1 x y | y &lt;- ys ] </code></pre>
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