On Wed, Jun 23, 2004 at 06:52:32PM +0100, MR K P SCHUPKE wrote:
> >So how do you debug problems like "Prelude.head: empty list"
> >in large programs?
> for precisely this reason - and the fact that I dont like bindings
> that can fail...
Note that pattern matching rather than deconstruction funct
On Wed, Jun 23, 2004 at 09:43:46PM +0100, Alastair Reid wrote:
> 2) If you don't want to put errors in the type system, you could instead use
>exceptions something along the lines of:
>
> myFunc 0 x = mapException
> (\ err -> show err ++ "when invoked by myFunc 0")
On Wed, Jun 23, 2004 at 10:39:08AM -0700, Fergus Henderson wrote:
> On 23-Jun-2004, MR K P SCHUPKE <[EMAIL PROTECTED]> wrote:
> > This may not be the right answer to the question (which is of
> > course lets write a debugger) - But I have never used a debugger,
> > and find them more or less the mo
>Thank you for the programming practice recomendation,
Sorry if it seemed like that... I was really trying to suggest
practical measures that someone could use in the absence of a
debugger - but I do feel that 'commercial quality' code
should be bullet proof, and of a different calibre to code
for
On Wednesday 23 June 2004 20:38, S. Alexander Jacobson wrote:
> It would be really nice if you could pass an
> error message down to every function that might
> fail. e.g. using implicit parameters*:
>
>myFunc 0 x = head x with ?failMsg="myfunc 0 caused the error"
Interesting. Two variations
Thank you for the programming practice
recomendation, but I would still prefer to
have something like the implicit parameters
solution I described.
The solution you describe forces you to put code
in functions to handle cases that are outside its
domain. Usually I just want to know what function
I like to write programs so functions cannot fail...
so head should really be:
maybeHead :: [a] -> Maybe a
maybeHead (a:_) = Just a
maybeHead _ = Nothing
etc...
The the calling function can do something like:
case maybeHead x of
Just y ->
It would be really nice if you could pass an
error message down to every function that might
fail. e.g. using implicit parameters*:
myFunc 0 x = head x with ?failMsg="myfunc 0 caused the error"
Head would be defined as e.g.
head [] = fail $ "empty list.\n" ++ ?failMsg
head (x:xs) = x
I
On 23-Jun-2004, Hal Daume III <[EMAIL PROTECTED]> wrote:
> On Wed, 23 Jun 2004, Fergus Henderson wrote:
>
> > On 23-Jun-2004, MR K P SCHUPKE <[EMAIL PROTECTED]> wrote:
> > > This may not be the right answer to the question (which is of
> > > course lets write a debugger) - But I have never used a
>Hmmm... chickens and eggs. I don't see a lot of *companies* using Haskell
Actually I have used Haskell in commercial projects... and am continuing to
do so. My development environment is Vim and GHC. Same one I have used for
C/C++ VHDL Perl, and anything else...
It is not that lack of GUI tool
>So how do you debug problems like "Prelude.head: empty list"
>in large programs?
I normally dont use head, but instead code:
case x of
(a0:_) ->
_ -> fail
for precisely this reason - and the fact that I dont like bindings
that can fail...
Keean.
___
On 23-Jun-2004, Ketil Malde wrote:
> > Thirdly, profiling seems to be incompatible with the use of ghci; there
> > doesn't seem to be any easy way to build a workspace so that you can
> > get stack traces and use ghci in that workspace at the same time.
>
> You can compile with: -prof -auto-all -
On 23-Jun-2004, MR K P SCHUPKE <[EMAIL PROTECTED]> wrote:
> This may not be the right answer to the question (which is of
> course lets write a debugger) - But I have never used a debugger,
> and find them more or less the most unfriendly and useless things
So how do you debug problems like "Prelu
At 11:48 23/06/04 +0100, Malcolm Wallace wrote:
If companies are willing to invest in development, they will get the
tools they want.
Hmmm... chickens and eggs. I don't see a lot of *companies* using Haskell
right now. And probably they won't until the tools they want are available
(and more...
MR K P SCHUPKE <[EMAIL PROTECTED]> writes:
> You either end up single stepping through a million lines of code,
> or you find the error is of a complex non-localised kind anyway.
Or you find that inserting a breakpoint (or waiting to hit an exception),
examining data structures which are either i
>Unless, of course, you have:
>1) A large program operating on a large body of data that takes a long time to
debugs logs go to a file, grep and awk let you quickly find things
>3) A complex library written by someone else which contains a bug or makes
before calling out print a funtion trace li
> Seeing as Haskell is apparently such a popular language these days,
> I don't suppose a working debugger would be too much to ask for, would it?
I agree.
> In case you're wondering, yes I have already tried using Hat and Buddha.
> But I'm trying to debug a real application, not a toy one, and n
This may not be the right answer to the question (which is of
course lets write a debugger) - But I have never used a debugger,
and find them more or less the most unfriendly and useless things
You either end up single stepping through a million lines of code,
or you find the error is of a complex
--- Simon Marlow <[EMAIL PROTECTED]> wrote:
> We would be delighted if someone would take Robert's
> hsdebug and port it
> to the non-speculative version of the compiler. In
> fact, this is one of
> the items on the GHC Task list:
>
>
http://sourceforge.net/pm/task.php?func=detailtask&project_tas
On 23 June 2004 09:27, Robert Ennals wrote:
> I wrote such a debugger as part of my PhD work. It is called
> "hsdebug" and you can read the Haskell Workshop paper on it here:
>
> http://www.cambridge.intel-research.net/~rennals/hw2003.pdf
>
> Unfortunately, HsDebug depends on Optimistic Evaluati
I wrote such a debugger as part of my PhD work. It is called "hsdebug" and you
can read the Haskell Workshop paper on it here:
http://www.cambridge.intel-research.net/~rennals/hw2003.pdf
Unfortunately, HsDebug depends on Optimistic Evaluation, and it seems unlikely
that Optimistic Evaluation w
Fergus Henderson <[EMAIL PROTECTED]> writes:
> Seeing as Haskell is apparently such a popular language these days,
> I don't suppose a working debugger would be too much to ask for, would it?
Hah. You're not supposed to debug, just stare at the code until
you become enlightened (why did you thin
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