Re: [Haskell-cafe] Memoization in Haskell?

On Friday 09 July 2010 01:03:48, Luke Palmer wrote:

On Thu, Jul 8, 2010 at 4:23 PM, Daniel Fischer wrote:

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On Friday 09 July 2010 00:10:24, Daniel Fischer wrote:

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You can also use a library (e.g. http://hackage.haskell.org/package/data- memocombinators) to do the memoisation for you.

Well, actualy, I think http://hackage.haskell.org/package/MemoTrie would be the better choice for the moment, data-memocombinators doesn't seem to offer the functionality we need out of the box.

I'm interested to hear what functionality MemoTrie has that data-memocombinators does not. I wrote the latter in hopes that it would be strictly more powerful*.

It's probably my night-blindness, but I didn't see an immediate way to memoise a simple function on a short look at the docs, like memo :: (ConstraintOn a) => (a -> b) -> a -> b , which Data.MemoTrie provides (together with memo2 and memo3, which data- memocombinators provide too). Taking a closer look at the docs in daylight, I see data-mc provides that out of the box too, the stuff is just differently named (bool, char, integral, ...) - which I didn't expect. So you could take it as an indication that I'm visually impaired, or as an indication that the docs aren't as obvious as they could be. Cheers, Daniel

Luke

* Actually MemoTrie wasn't around when I wrote that, but I meant the combinatory technique should be strictly more powerful than a typeclass technique. And data-memocombinators has many primitives, so I'm still curious.