Re: [Haskell-cafe] [newbie question] Memoization automatic in Haskell?

On 12 Jan 2008, at 3:30 PM, David Benbennick wrote:

On 1/12/08, Henning Thielemann wrote:

...

Caching is not the default, but you can easily code this by yourself: Define an array and initialize it with all function values. Because of lazy evaluation the function values are computed only when they are requested and then they persist in the array.

But how can I implement memoization for a more complicated function? For example, perhaps I want to memoize

f :: String -> Int -> Double -> String -> Bool

In Python, it's pretty easy to memoize this. How can I do it in Haskell? I suspect the only way would involve changing the function signature to use IO or ST.

It would be nice if I could just tell the compiler "I command you to memoize this function", and have it produce the required code automatically.

You can cache anything using mutable hash tables, as you know, and googling will find you `function's in Haskell that do this for you. jcc