[Haskell-cafe] Memoization/call-by-need

Román González romanandreg at gmail.com
Thu Sep 16 14:07:54 EDT 2010


Maybe this pdf can enlighten you a little bit about memoization and lazy
evaluation in Haskell =>



I feel that there is something that I don't understand completely:  I have
> been told that Haskell does not memoize function call, e.g.

> slowFib 50

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 "lazy evaluation
> with memoization"

> I understand that

> fib50 = slowFib 50

will take a while to run the first time but be instant each subsequent call;
> does this count as memoization?

> (I'm trying to understand "Purely Functional Data Structures", hence this


          Alex R
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