On Friday 09 May 2008 16:38:55 Jeff Polakow wrote:
> Hello,
>
> > We investigated alternative languages to diversify into last year and
> > Haskell
> > was one of them. The single biggest problem with Haskell is that it is
> > wildly
> > unpredictable in terms of performance and memory consumption.
>
> This is only the case if you don't understand lazy evaluation.

Simon Peyton-Jones told me that. I am sure you will agree that he understands 
lazy evaluation.

> This is no 
> different from OCaml, or any language. One must understand the operational
> semantics to write efficient code. Imagine how a C programmer feels when
> writing OCaml without knowing to make functions tail-recursive.

Tail calls have simple rules. Graph reduction of a lazy program with 
optimizing rewrites and strictness analysis does not adhere to simple rules.

Simple rules => predictable.

> I wonder if similar complaints (unpredicatable performance, memory use,
> dearth of practical information) will arise about F# as it starts to be
> widely adopted in the real world.

F# has long since overtaken all other functional languages in terms of 
industrial uptake and I have not heard that complaint from anyone. Like 
OCaml, it follows simple rules and is predictable as a consequence.

Some of the rules are very different in F#. For example, nested closures 
degrade performance in OCaml but improve performance in F#.

This may well change as we transition to manycore and parallelism makes 
performance unpredictable.

-- 
Dr Jon D Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/products/?e