Indeed GHC does not attempt to retain the order of alternatives, although
a) it might be possible to do so by paying more attention in numerous places
b) GHC may do so already, by accident, in certain cases
Observations:
* The issue at stake is a small one: not the *number of tests* but *which
You could imagine a pragma to say which branch is likely.
f p1 = e1
f p2 = {-# LIKELY #-} e2
f p3 = e3
Is there some way to propagate pragmas through core transformations?
-- Lennart
On Wed, Mar 25, 2009 at 9:18 AM, Simon Peyton-Jones
simo...@microsoft.com wrote:
Indeed GHC does not attempt
| You could imagine a pragma to say which branch is likely.
| f p1 = e1
| f p2 = {-# LIKELY #-} e2
| f p3 = e3
|
| Is there some way to propagate pragmas through core transformations?
Not robustly. We do have Notes attached to core, which are more or less
propagated though, but I make not
On my obscure configuration (GHC 6.10.1, with pkgenv activated, on
Fedora Linux rawhide running on a VirtualBox x86 VM with hardware
virtualisation enabled), running strace on cabal causes it to
misbehave, as described below.
I don't know whether this is due to a bug in cabal, the GHC
runtime,
On Mon, Mar 23, 2009 at 10:53:19AM +0100, José Pedro Magalhães wrote:
Bad interface file: C:\Program Files
(x86)\Haskell\syb-0.2.0.0\ghc-6.10.1.20090314\Data\Generics.hi
Something is amiss; requested module syb:Data.Generics differs from
name found in the interface file
Robin Green wrote:
On my obscure configuration (GHC 6.10.1, with pkgenv activated, on
Fedora Linux rawhide running on a VirtualBox x86 VM with hardware
virtualisation enabled), running strace on cabal causes it to
misbehave, as described below.
I don't know whether this is due to a bug in
Manuel M T Chakravarty wrote:
jutaro:
This is the first answer I got from the gtk2hs mailing list. Please
consider
this issue seriously.
Well there is a simple fix as Simon Marlow wrote,
The fix is fiarly easy: use Foreign.Concurrent.mkForeignPtr with a
foreign import.
In fact, if as Axel
Hello Ian,
2009/3/25 Ian Lynagh ig...@earth.li
On Mon, Mar 23, 2009 at 10:53:19AM +0100, José Pedro Magalhães wrote:
Bad interface file: C:\Program Files
(x86)\Haskell\syb-0.2.0.0\ghc-6.10.1.20090314\Data\Generics.hi
Something is amiss; requested module syb:Data.Generics
(thanks to Simon PJ for an excellent summary of the issues)
Lennart Augustsson wrote:
You could imagine a pragma to say which branch is likely.
f p1 = e1
f p2 = {-# LIKELY #-} e2
f p3 = e3
Is there some way to propagate pragmas through core transformations?
I just thought I'd mention the
When you tried switching Nil and Cons, did you try it on many examples?
For a single example a 2-3% could be easily attributed to random
effects like different instruction cache hit patterns. If you get it
consistently over several programs then it seems likely to mean
something, but I'm not sure
On Mar 25, 2009, at 5:18 AM, Simon Peyton-Jones wrote:
Indeed GHC does not attempt to retain the order of alternatives,
although
a) it might be possible to do so by paying more attention in
numerous places
b) GHC may do so already, by accident, in certain cases
...
* Which plan performs
| very long list than the Cons-before-Nil order I wanted), but it is
| very frustrating if I'm not even given the chance because GHC
| sorts the alternatives, not even according to its own interpretation
| of branching performance, but completely arbitrarily!-)
All I'm saying is that GHC has
I don't find ordering of patterns appealing, I find it scary! I order
my patterns according to the semantics I desire, and then additionally
by what looks pretty. I'd like it if whatever cleverness GHC can work
is used rather than requiring me to think. If the order of patterns is
to become
On Wed, 2009-03-25 at 09:18 +, Simon Peyton-Jones wrote:
* More promising might be to say this is the hot branch. That information
about frequency could in principle be used by the back end to generate better
code. However, I am unsure how
a) to express this info in source
On March 25, 2009 21:38:55 Claus Reinke wrote:
If you don't have that kind of control, and generate code as if
there were no hardware-level optimizations, the resulting
mismatch will manifest in hard-to-predict variations in
performance, making it difficult to see how much or why
speed is
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