I feel that there is something that I don&#39;t understand completely:  I have been told that Haskell does not memoize function call, e.g.<div>&gt; slowFib 50</div><div>will run just as slowly each time it is called.  However, I have read that Haskell has call-by-need semantics, which were described as &quot;lazy evaluation with memoization&quot;</div>
<div><br></div><div>I understand that</div><div>&gt; fib50 = slowFib 50</div><div>will take a while to run the first time but be instant each subsequent call; does this count as memoization?</div><div><br></div><div>(I&#39;m trying to understand &quot;Purely Functional Data Structures&quot;, hence this question)<br clear="all">
<br>-- <br><div dir="ltr"><div>          Alex R</div></div><br>
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