> Date: Fri, 19 Feb 1999 09:41:58 +0100 (MET)
> From: Lennart Augustsson <[EMAIL PROTECTED]>
> CC: [EMAIL PROTECTED], [EMAIL PROTECTED],
> [EMAIL PROTECTED]
>
>
> > Concerning 'rapid access' you found in docs - it is hard to believe
> > this access is as fast as in C array - i mean changing X[i] in array
> > X. Because when this change is done fast, it is a side effect, breaks
> > functionality.
> Extracting values from an array can be as fast as in C. The tricky
> part is contructing the array. The Haskell Array module provides
> one way of constructing monolithic arrays, i.e., arrays that are built
> once and never again modified.
> But there are other ways, e.g., using ST monad which allows incremental
> construction of the array.
>
> -- Lennart
>
This reminds me of a question I could not solve on my own yet (due to
lack of an operational profiler for the most part): Is it possible that
ghc knows how to transform Array data structures into destructive
arrays in some settings?
I had an algorithm with a terrible time complexity and wrote an
implementation using purely functional Arrays. Since the runtime was
still to bad, I tried ST together with MutableArrays instead, but the
runtime got worse.
I don't have the time to figure out the details right now, but if you
plan to stay interested in them for a longer period, tell me and I will
give you more information when I work on the problem again. (It's still
possible that it's a bug in my code, however.)
-Matthias
--
Max-Planck-Institut für Informatik | DFKI
[EMAIL PROTECTED] | [EMAIL PROTECTED]
http://www.mpi-sb.mpg.de/~fis |
