On 13 Aug 2008, at 13:18, [EMAIL PROTECTED] wrote:
G'day all.
Quoting Thomas Davie <[EMAIL PROTECTED]>:
To be honest, ghc compiles things so fast (at least on any of
my systems) that I couldn't care less if it took 10 times as long
(I would
however like some added convenience for that time spent)
Have you ever compiled GHC itself? Just curious what you'd think
about
a 10x speed hit there.
On the machine I'm sat at now, it takes 20 minutes. Secondly, you
would *only* pay the speed penalty when you had cyclic includes, and
you didn't use the flag to use an hi-boot file, so it would continue
to take 20 minutes.
If it helps, think about the lifetime of a program. If you assume
that
a program grows linearly over time, and that recompilations occur at
a roughly constant rate, it follows that the time spent recompiling
is O(n^2). Constant factors matter.
But the penalty would be no where near that big -- unless you happened
to have *all* your modules depend on *all* other modules.
If I compile a module on which lots of other modules depend,
I have to do lots of recompilation... If I compile a module which
is in
a cyclic dependancy group, I have to do lots of recompilation, I
don't
see that there's a difference here.
If you only change the implementation of a module, not its interface,
you don't need to recompile anything that imports it. (At least, this
is true at -O0, which if you care about fast recompilation because
you're deep in development, you're probably doing.)
Well, if this turned out to take a long time, then I'd probably switch
to writing an hi-boot file... Something that I wouldn't have to waste
time doing at all if it happened that ghc was still "fast enough"
without providing one.
Bob
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
