can a lazy language give fast code?

Andrew J Bromage
Tue, 30 Jul 2002 10:30:30 +1000

G'day all.

On Mon, Jul 29, 2002 at 10:23:05AM +0100, Simon Marlow wrote:

> Many of those programs can be written differently to improve
> performance.

To be fair, Doug admits this as well as a lot more:

Despite these flaws, I did notice that ghc is right in the middle in
his CRAPS score system (which is really interesting; all due respect
to the GHC guys, but I expected it to be lower <g>).

I also noticed that the majority of cases where Haskell does
significantly worse than average are "same way" tests, designed to test
the performance of various constructs (e.g. array access, dictionary
lookup) as opposed to "same thing" tests, designed to test native

In the end, though, benchmarks ignore one of the most important rules
of software performance: "throughput" (i.e. the amount of processing
that your system can do just prior to being overloaded) is almost never
the most important consideration.  Other considerations such as
flexibility, robustness, responsiveness and scalability are almost
always more important.

I've thought for a while that what we need is more benchmarks like
pseudoknot: Real tasks which real people want to do.  Computing
Ackermann's function is all well and good, but when's the last time you
actually needed to compute it in a real program?

Off the top of my head, some "real" tasks which could be benchmarked

	- MPEG video compression.

	- Code scheduling/register allocation for a CPU like the
	  MIPS/Alpha or even the IA64.

	- Fluid simulation.

	- Solving chess problems.

Andrew Bromage