However, when I actually tried this
out, I couldn't get it to compile.
So I wound up back with trace. This
does compile, and I think it does pretty much what we want in a "noninvasive"
way, using unsafePerformIO via trace.
import Debug.Trace
t = foldr (+) 0 ( monitorprogress f
[1..10000] )
monitorprogress f xs = map g $ zip
[1..] xs
where g (i,a) | f i == True
= trace (show i) a
| otherwise = a
f x | x `mod` 1000 == 0 = True
| otherwise = False
Thomas Hartman/ext/dbcom@DBAmericas Sent by: haskell-cafe-bounces@haskell.org
11/29/2007 10:43 AM
To
haskell-cafe@haskell.org, droundy@darcs.net
cc
Subject
Re: [Haskell-cafe] Progress indications
Obviously heaps better than what I initially proposed.
However, I would argue to go boldly with unsafePerformIO, which is the
same thing Debug.Trace uses
In particular, you wouldn't be able to use the unsafeInterleaveIO version
to do a progress indicator for the function I initially proposed
> t = foldr (+) 0 [1..10000]
since your lift would wind up being lifted into IO. But you would be able
to use the unsafePerformIO version, just like in what I initially proposed
you could use trace.
t = foldr (+) 0 ( lessSafeMonitoryProgress f [1..10000] )
where f i | i mod 1000 == 0 = (putStrLn . show ) i
| otherwise
= return ()
Make sense?
thomas.
David Roundy <droundy@darcs.net>
Sent by: haskell-cafe-bounces@haskell.org
11/28/2007 06:16 PM
To
haskell-cafe@haskell.org
cc
Subject
Re: [Haskell-cafe] Progress indications
On Wed, Nov 28, 2007 at 05:58:07PM -0500, Thomas Hartman wrote:
> maybe Debug.Trace? like...
>
> import Debug.Trace
>
> t = foldr debugf 0 [1..10000]
>
> f :: Int -> Int -> Int
> f = (+)
>
> -- same typesig as f
> debugf :: Int -> Int -> Int
> debugf x y | y `mod` 1000 == 0 = x + (trace (show y) y)
> debugf x y = x + y
Or, more flexibly:
import System.IO.Unsafe ( unsafeInterleaveIO )
monitorProgress :: (Int -> IO ()) -> [a] -> IO [a]
monitorProgress f xs = mapM f' $ zip [0..] xs
where f' (n,x) = unsafeInterleaveIO (f n >> return x)
by using unsafePerformIO instead of unsafeInterleaveIO, but that seems
slightly scary to me.
In any case, you can stick this on whichever of the lists you want to
monitor the progress of.
--
David Roundy
Department of Physics
Oregon State University
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
---
This e-mail may contain confidential and/or privileged information. If
you
are not the intended recipient (or have received this e-mail in error)
please notify the sender immediately and destroy this e-mail. Any
unauthorized copying, disclosure or distribution of the material in this
e-mail is strictly forbidden._______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
---
This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.