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    <p>I think you're looking for is the '<em>Derived arrays</em>' section in the Data.Array documentation: <a href="http://hackage.haskell.org/packages/archive/array/latest/doc/html/Data-Array.html#5" rel="noreferrer">http://hackage.haskell.org/packages/archive/array/latest/doc/html/Data-Array.html#5</a> which houses the function:</p> <blockquote> <p><strong>ixmap</strong> :: (Ix i, Ix j) => (i, i) -> (i -> j) -> Array j e -> Array i e</p> <p>ixmap allows for transformations on array indices. It may be thought of as providing function composition on the right with the mapping that the original array embodies.</p> <p>A similar transformation of array values may be achieved using fmap from the Array instance > of the Functor class.</p> </blockquote> <p>The following code:</p> <pre><code>ixmap newBounds trans backingArray </code></pre> <p>would return an array with bounds <code>newBounds</code>, and when indexed with <code>!i</code>, the <em>index transformation function</em> is applied onto the index <code>i</code> before being used to index <code>backingArray</code>.</p> <hr> <p><strong>Example</strong> if you had the array "Hello World" (helloWorldArray below) and you want to only see "ell" as a derived <em>zero-based</em> (sub-)array:</p> <pre><code>&gt; let helloWorldArray = listArray (0,length str - 1) str -- 0-based array where str = "Hello World" &gt; let ellArray = ixmap (0,2) succ helloWorldArray -- also 0-based array &gt; ellArray ! 0 'e' &gt; ellArray ! 1 'l' &gt; ellArray ! 2 'l' </code></pre> <p>Here we say that our new array <code>ellArray</code> has indices from <code>0</code> through <code>2</code>. Our index transformation is simply to add one (<code>succ</code>), because we want to map the index range <code>[0..2]</code> to <code>[1..3]</code> in the original <code>helloWorldArray</code>.</p> <p>Of course, <code>ixmap</code> is abstract enough to capture any index transformations: even as to view 2 dimensional arrays as 1 dimensional arrays and vice-versa. It's better to think of it as creating a 'view' onto array data <em>rather</em> than a 'sub-array' function.</p> <p>For more examples you can look here: <a href="http://zvon.org/other/haskell/Outputarray/ixmap_f.html" rel="noreferrer">http://zvon.org/other/haskell/Outputarray/ixmap_f.html</a></p>
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