[Haskell-cafe] Haskell performance (again)!

[Jason Dagit]

On 10/8/06, ihope <ihope127 at gmail.com> wrote:
> On 10/8/06, Yang <hehx0sk02 at sneakemail.com> wrote:
> > And do most (experienced) Haskell
> > users sacrifice cleanliness for speed, or speed for cleanliness?
>
> Keep the internals of your code--that which will be looked at a
> lot--fast and ugly, while the rest can be clean. If you have a
> function that does something very simple, but the "pretty" way to do
> it takes a second to run while the ugly way is much, much faster, use
> the pretty one if it's only going to be needed once or twice. It's
> certainly not the kind of thing you want to fold your lists with: use
> the ugly version for that.
>
> Also, if you want, you can write both a pretty version and an ugly
> version, and put the pretty version in comments while the ugly version
> does all the real work.

Another good idea when you have a pretty version which is easy to
verify for correctness and an ugly version that is harder to verify is
to use QuickCheck or SmallCheck and define a property that says both
versions are equal for all inputs.  Ugly code is notorious for holding
bugs, but doing this would help test the ugly code.

Jason