[Haskell-cafe] memory-efficient data type for Netflix data - UArray Int Int vs UArray Int Word8

Manlio Perillo manlio_perillo at libero.it
Thu Feb 26 07:00:55 EST 2009

Kenneth Hoste ha scritto:
> Hello,
> I'm having a go at the Netflix Prize using Haskell. Yes, I'm brave.
> [...]
> To see if I could efficiently represent the data set in this way, I 
> wrote a small
> Haskell program (attached) which uses the following data type:

 From what I see, to append a new integer to the Array, you convert the 
array to a list, append the new element to the list, and then convert to 
array again.

Isn't this a bit inefficient?

The uvector package implements a vector of unboxed types, and has an 
snocU operation, to append an element to the array.

I don't know how efficient it is, however.

By the way, about uvector: it has a Stream data type, and you can build 
a vector from a stream.

But how this work and how (if any) the stream data is integrated with 
other packages?
The package documentations seems to be still incomplete.

 > [...]

Regards  Manlio Perillo

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