Hi Dougal,
It's cross platform, and will use GHC and Hugs if they are already installed.
Thanks
Neil
On 8/15/07, Dougal Stanton [EMAIL PROTECTED] wrote:
On 15/08/07, Asumu Takikawa [EMAIL PROTECTED] wrote:
== GuiHaskell
Guihaskell is a graphical REPL using PropLang, a GUI combinator
Hi
So what I noticed that A Gentle Introduction to Haskell mentioned
that wild-cards are useful in constructors. For example:
head (x:_) = x
So, does that offer any performance benefits over:
head (x:xs) = x
No. They are exactly the same. _ simply means a new unique name.
Or is it
Hi,
The Haskell desugaring for list comprehensions is given in:
http://haskell.org/onlinereport/exps.html#list-comprehensions
All the rules seem to be left to right rewrites, apart from the second
one, which seems to be right to left. Is there some deep reason for
this, or is this accidental.
Hi
Sorry for the noise, I've now realised they are a left to right
rewrite system, the second rule is required to set up the base case.
Thanks
Neil
On 8/19/07, Neil Mitchell [EMAIL PROTECTED] wrote:
Hi,
The Haskell desugaring for list comprehensions is given in:
http://haskell.org
Hi
will 6.7 be released, or will only 6.8 be ?
6.7 is the HEAD branch, 6.8 will be released.
-in that case, does the 6.8 branch means the freeze is on, and what would be
the target for 6.8 ? Q3/2007 ? Q4 ?
Soon, in the next month - according to latest targets/estimates.
( context: I am
Hi
Distribution/Simple/InstallDirs.hs:267:36:
Not in scope: `dropDrive'
[EMAIL PROTECTED]:~/installs/cabal-head/caballs -l `which ghc`
lrwxrwxrwx 1 root root 31 2007-08-20 11:08 /usr/local/bin/ghc -
/usr/local/bin/ghc-6.7.20070816
You'll need to upgrade the filepath library as well,
Hi
Wait, you're saying that ghc can produce pure c-code, that doesnt
contain any assembly code, and that runs as fast as ghc code that does
contain assembly?
No. It can produce pure C code (unregistered), but to get high
performance it processes the output assembly afterwards (registered).
Hi Peter,
liftV1 f (V x y) = V (f x) (f y)
liftV2 f (V x1 y1) (V x2 y2) = V (f x1 x2) (f y1 y2)
liftM1 f (M x y) = M (f x) (f y)
liftM2 f (M x1 y1) (M x2 y2) = M (f x1 x2) (f y1 y2)
Both pairs of lift functions have almost identical implementations. Can I
Hi
sum (enum 1 10) =
sum' 0 (enum 1 10) =
...
sum' 36 (9 : enum (9+1) 10) =
(sum' $! (36+9)) (enum (9+1) 10) =
sum' 45 (enum (9+1) 10) =
sum' 45 [] =
45
(I need to find some way to automate making these trails
Hi
Other rules that could be interesting are:
forall a b. fromInteger a + fromInteger b = fromInteger (a + b)
forall a b. fromInteger a * fromInteger b = fromInteger (a * b)
This is wrong, since the class function can do what it wants. Imagine:
instance Num String where
(+) = (++)
Hi
If Num obeys ring axioms, fromInteger is a perfectly fine
ring-homomorphism. (It's also the first or second homomorphism taught.)
Does Int obey these axioms? I'm thinking that assuming properties
about things such as numbers is very likely to go wrong very quickly.
Monads you might be able
Hi
factors :: Int - [Int]
factors n = [x | x - [1..n], n `mod` x == 0]
prime :: Int - Bool
prime n = factors n == [1, n]
My vague intuition said we either need factors or we don't, we do
because we need to perform the test, so we compute it. That's wrong,
so a posteriori the
Hi
Its (==) isn't
reflexive (is it transitive? probably, at least if there aren't too many
optimizations, but floating-point transitive equality isn't very useful).
It's not even referentially transparent in all cases. a == b may fail
while the double's are in the high precision registers,
Hi
Yeah, the precise details may vary, even :) But for teaching, an
automatic tool that does graph reduction would be great. I don't mind
if it's sloppy (directly apply definitions pattern matching VS
everything is a lambda abstraction) and only does simply typed lambda
calculus (no
Hi
I'm new to WinHugs, what's wrong with isUpper of my WinHugs?
Nothing. The book/tutorial you are going from is out of date. Before
using the isUpper/isLower functions you first have to type :load
Char:
Hugs :load Char
Hugs filter isUpper ABCDEfgh
ABCDE
The :load Char loads the Char module
Hi
- Blogging software. (Because there isn't enough of it in the world yet.)
Hope (google: Haskell Hope)
- A wiki program. (Ditto.)
Flippi (google: Haskell Flippi)
- A general CMS.
Hope
- An interactive function plotter. (GNUplot is nice, but it can't plot
recursive functions...)
None
Hi
Flippi (google: Haskell Flippi)
...and yet haskell.org uses WikiMedia? (Which is written in something
bizzare like Perl...)
Yes, but WikiMedia is a result of years of work, Flippi is a lot less.
Wikipedia uses WikiMedia - its a tried and proven solution.
- A graphical programming
Hi
Another option would be to port the yhi bytecode interpreter to run on
PalmOS. I tried this, but I ran into three problems:
1. libgmp dependency
This is no longer an issue, we now have a flag to not require libgmp,
which makes type Integer = Int
2. build system requires Python
Hi Alexteslin,
I just came across with this question on the exam and can not think of
implementing it.
mapPair :: (a - a - a) - [a] - [a]
such that mapPairs f [x1, x2, x3, x4...] = [f x1 x2, f x3 x4,...]
I would implement this using direct recursion. As a starting point,
the standard
Hi
mapPairs :: (a - a - a) - [a] - [a]
mapPairs f [x] = [x]
mapPairs f [] = []
mapPairs f (x:xs) = f x (head xs) : mapPairs f (tail xs)
It looks like it works, but you can get a better version by changing
the last line:
mapPairs f (x:y:zs) = ... - left as an exercise, but no need for head
Hi
Bring back HaWiki!
I couldn't agree more! We built up an incredible array of articles, by
fantastic authors with stunning content - which we then deleted... I
learnt much from the old wiki, and it would be a shame if others
didn't get that opportunity.
Of course it should be static only,
Hi
There are two entirely separate issues in this thread - let's not confuse them.
1) The old HaWiki content is good and unavailable. I want it made
available, in whatever form is appropriate. Please :-)
2) Licensing - the old content cannot be dumped onto the new wiki. My
personal view is who
Hi Neil,
Given that GHC 6.8 is just around the corner and, given how it has
re-organised the libraries so that the dependencies in many (most/all)
the packages in the hackage DB are now not correct.
Is there a plan of how to get hackage DB up to speed with GHC 6.8 ?
I think whatever we go
Hi
* Create sophisticated GUIs.
Gtk2hs. Could do with a nice wrapper on that, but Conal is doing some
interesting stuff, and I've got PropLang on the back burner. People
are thinking the right thoughts, it just needs time.
* Read and write standard binary file formats. (Images, compressed
Hi
Data.Binary is the low level frameworks, now people can pick up the rest.
Last time I checked, there's about half a dozen binary packages. All
incompatible. All with different design. Seriously not obvious which one
to use...
Data.Binary is the answer,
Hi
I have the following page bookmarked:
http://haskell.org/ghc/docs/latest/html/libraries/
Just bookmark: http://haskell.org/hoogle
It's not perfect, but it probably solves lots of your problems.
A tip is to use Firefox's search as you type feature if you know the
module name.
This
Hi
(Some list operations are too expensive with ByteString but for most
string processing it's perfectly fine and much faster than String).
I'm sure it's true, but it's quite irrelevant to my question, which is
why is using getChar so much slower than using getContents?
Buffering, blocks
Hi Peter,
It does not seem to have shortcut keys for reload, edit, etc...
When do you use reload? WinHugs automatically reloads modified files,
so I've never felt the need to reload things. Similarly for edit,
typing just edit on its own isn't that useful unless you give it a
module.
However,
Hi Peter,
Automatic reloading is of course THE best solution, and that's already
in :-) Maybe it could help new users to display a simple message into
the WinHugs statusbar like module XXX reloaded after external
modification at HH:MM:SS) or something? But that's really minor.
That would be
Hi
I've never really understood what the benefit of this is... I mean,
Google make the Google toolbar, but what's the point? Why not just
click on the Google bookmark and type in your search? What benefits does
installing a special addon provide?
You can setup firefox so in the location
Hi Peter,
The way I see it as a newcomer, Haskell shifts the typical imperical
programming bugs like null pointers and buffer overruns towards
space/time leaks, causing programs that either take exponentially long
to complete, stack overflow, or fill up the swap file on disc because
they
Hi
Well, I actually meant more something like the imperative equivalences
of code coverage tools and unit testing tools,
hpc and HUnit cover these two things pretty perfectly. hpc will be in
GHC 6.8, and its really cool :-)
because I've read
rumors that in Haskell, unit testing is more
Hi
there is no runtime representation of type available for programmatic
representation
Data.Typeable.typeOf :: Typeable a = a - TypeRep
there is no runtime representation of the type-inferencing or checking
machinery
Pretty much, no. The GHC API may provide some.
there is no runtime
Hi
A more serious point is that in some cases we might want take to
underapproximate, or zip to truncate (or tail [] = [] ?). I don't
think there's
always a clear library choice here.
I have a zipWithEq function I often use, which crashes if the zip'd
lists aren't equal. I also have tailSafe
Hi
The same should apply to head and tail. head or tail of [] should be [].
What does the list think?
Disagree, strongly. Its not even possible for head, since [a] - a.
Wadler's theorems for free states that if head is given an empty list
the _only_ thing it can do is crash.
Thanks
Neil
Hi
Although I appluad the semantics of the safe package, I'm not delighted
with the idea of replacing our concise elegant standard library names
with uglyAndRatherLongCamelCaseNamesThatCouldBePerlOrEvenJava though.
Conciseness of expression is a virtue.
They aren't that long - merely an
Hi
Similarly, I expect foo and foo' to be equivalent, except for strictness
properties, but perhaps an underscore could be used for slightly
different behaviors (interpretations, as it were)? tail_ or zip_,
anyone?
There are 4 variants of tail:
tail :: [a] - [a] -- normal
tailDef :: [a] -
Hi
Is there a reason for not having
tailM :: Monad m = [a] - m [a]
which, at least for me, is much more useful?
No, that probably is a much more sensible choice. Patches welcome :)
Thanks
Neil
___
Haskell-Cafe mailing list
Hi
From the logical point of view tailMay is the right one.
It pushes the error handling to the caller programm.
tail = fromJust . tailMay
The error messages suffer:
tail [] = error: fromJust Nothing
That's why I supplied tailNote, where tailNote foo broke its
invariant! [] gives the
Hi
Monomorphism restriction? Replacing fold with foldRegsUsed would work
because there's a type signature for foldRegsUsed.
That looks like it. Another solution would be:
fold = foldRegsUsed
becomes:
fold x = foldRegsUsed x
Now the monomorphism restriction doesn't kick in because fold
Hi
Would you care to explain why you have this aversion to libs that aren't
bundled with ghc?
They are less stable and have less quality control. It is also an
additional burden for a user to install the library to get the program
working.
cabal-install should fix the second. Some useful
Hi
What's bad about stagnation is that nobody will bother to produce
anything better (at least not as a fully polished publicly available
open source project), precisely because they have little chance of
achieving a user base exceeding 1 (at least not if the attitude of
David and Neil is
Hi
They are less stable and have less quality control.
Surely you jest? I see no evidence of this, rather the contrary in fact.
No, dead serious. The libraries have a library submission process.
Compare me changing my tagsoup library, to me changing my filepath
library which comes bundled
Hi
What is the process for the inclusion of modules / packages in ghc, hugs and
other compilers interpreters?
Propose to have the packaged added. There is a very low chance of this
being accepted. The only packages to have recently been added were
FilePath and ByteString, both of which were
Hi
I think there is a niche for a subset of the hackage libraries providing
an officially sanctioned standard library collection. Currently,
hackage includes, well, everything. As such, it is a useful resource,
but it would be useful to have a partitioning into two levels, where the
SLC
Hi Barney,
This may be of interest, since all types already have an Int
associated with them:
http://haskell.org/ghc/docs/latest/html/libraries/base/Data-Typeable.html#v%3AtypeRepKey
Thanks
Neil
On 9/18/07, Barney Hilken [EMAIL PROTECTED] wrote:
In order to make my records system
Hi
okay, but this fails in some cases. i wrote a package to obtain
financial quotes. yahoo changed the webservice url on me. i rolled out
a change within a day. in your model, people suffer a broken service
for two weeks.
I don't think Yahoo will change the syntax or semantics of filepaths
Hi
who has vty for haskell?
I can't find the right one so who can mail one to me ?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/vty-3.0.0
hackage has a lot of packages, and is always a good place to start a search.
Thanks
Neil
___
Hi
Now why isn't pattern matching lazy by default? This seems odd for a
newbie since everything else is lazy by default.
f ~(x:xs) = rhs
f ~[] = rhs'
Now guess what f [] does...
If you use a where binding then pattern matching is lazy.
Thanks
Neil
Hi Peter,
During a googling session, I can across (Win)HIPE, a visualization program
for the functional language HOPE. See
http://dalila.sip.ucm.es/~cpareja/winhipe
IMHO a similar tool would be a nice for learning/teaching Haskell; does
that exist, or something else that comes close?
Hi
Yes, Hat does this http://www.haskell.org/hat/ (if you can get it to
work, I typically have little success)
Thanks. WinHIPE uses graphics and animation. If briefly encountered Hat
before, but I had the impression it did not visualize the graphs using
graphics, only text. Is this
Hi Peter,
So I grabbed ghc-6.7.20070824 (=the latest one for Windows I could find)
and the extra-libs, compiled and installed the GLUT package (which I
needed), but when I compile my library, I get
Could not find module `Data.Map':
it is a member of package containers-0.1,
All dependencies etc. have changed when going to 6.7/6.8 - you are
probably better off using 6.6.1 for now.
That's a petty. I really would like to experiment with the debugger :-)
Me too! A proper release of GHC 6.8 is very nearby, so you should get
your wish then.
Thanks
Neil
Hi
f = f
and then try to evaluate 'f' in GHCi, as one would expect, the interpreter
never returns an answer.
The funny thing is that, while it is stuck in an infinite loop, GHCi doesn't
seem to use any CPU time at all.
It's called a black hole. The runtime can detect that f directly
Hi
I'm not sure, but since it would require the detection of an evaluation
that does not terminate, it comes down to the halting problem, which is
not generally solvable. Maybe the experts can confirm my intuition?
I think your intuition is off. This isn't the problem of detecting
that a
Hi
The haskell-cafe@ mailing list is more appropriate for messages such
as this. haskell@ is just for announcements (it should be called
haskell-annouce@ !)
* Lambda calculus - the basis of functional languages
* Category theory - where all these mysterious things like monads,
arrows, and
Hi
I've just replied to another first poster with wrong list. Its
entirely not their fault, but its also probably a bit off-putting that
your very first post gets a (very polite) you got it wrong message.
To steal the reasons and explanations from Ian:
-
pretty much what
Hi
I agree. Unless... do some people subscribe to haskell@ (not
haskell-cafe@) and like the existing stuff that's sent there (not all
announcements... I'm not sure if I'd call e.g. Oleg's occasional
demonstrations announcements even)?
There are four things sent to the haskell list@
1)
Hi
Forgive me, but I would much prefer a newsgroup to a mailing list.
True, I could unsubscribe now and just browse the mailman archives -
but for posting, I'd have to temporarily re-subscribe, which is awkward.
(Indeed that's the only reason I'm not doing it.)
I believe you can post from
Hi Vimal,
I was surprised to find out that the following piece of code:
length [1..] 10
isnt lazily evaluated!
The problem is that Int and Integer are both eager. It is possible to
write a lazy peano number based data type, but I'm not aware of anyone
who has - I have half the code (in
Hi
In this world, use length (take 11 [1..]) 10...
not (null (drop 10 [1..])) is surely faster (not tested...)
Faster? There might be a few microseconds in it.
Clearer? Possibly... ;-)
lengthNat [1..] 10
Couldn't be clearer, and can be made to work perfectly. If anyone does
want to
Hi
lengthNat [1..] 10
Couldn't be clearer, and can be made to work perfectly. If anyone does
want to pick up the lazy naturals work, I can send over the code (or
write it yourself - its not hard!)
Um... isn't a lazy natural just a list with no data, where the list
length encodes a
Hi
Pretty much, yes.
So I just need to write
newtype LazyNatural = LazyNatural [()]
or
data Nat = Zero | Succ Nat
it's your choice really.
and then add some suitable instances. ;-)
Yes. Lots of them. Lots of instances and lots of methods.
Hey, the length function would then just
Hi
I'm guessing there's going to be fairly minimal performance difference.
(Or maybe there is. My way uses a few additional pointers. But it also
allows me to elegantly recycle existing Prelude list functions, so...)
I think we can safely assume that people using peano numbers aren't
actually
Hi
show_system =
unlines .
zipWith
(\l ms -
Eq ++
show l ++
: ++
(concat $ intersperse + $ zipWith (\n x - x ++ x ++ show
n) [1..] (init ms)) ++
= ++
last ms
)
[1..] .
map (map (take 8 . show))
And people complain that
Hi
complex. The input is quite simple (it's a bunch of numbers), the output
is quite simple (it's a neatly formatted string), but the process in the
middle is... a mess. I'd like to find a more readable way of doing stuff
like this. It's not just this specific function; any general hints
Hi Peter,
This is of course very easy to do manually, but does a command line tool
exist for extracting source code from literate Haskell files?
Cpphs is the perfect tool to do this.
Thanks
Neil
On 9/30/07, Peter Verswyvelen [EMAIL PROTECTED] wrote:
Thanks,
Peter
Hi Peter,
It sounds like the problem is that you need to convert it to Hugs,
rather than WinHugs specific (which might put a few people off looking
to see if they can help). Perhaps an email to the author of the
library might help you find if they would be interested in doing a
port to Hugs.
Hi Peter,
There is a Dotnet tree in the Hugs source code files, which I believe
is what supports dotnet. As far as I am aware, it probably won't work.
A windows developer may be able to build it, but I've never tried.
You might also be interested to know that Yhc supports --dotnet to
generate a
Hi Peter,
Also typing runhugs Setup.hs configure fails with
runhugs: Error occurred
ERROR c:\program
files\winhugs\packages\base\Text\ParserCombinators\ReadP.hs:156
- Syntax error in type expression (unexpected `.')
This is because Cabal gets it wrong. You need to type runhugs -98
Setup
Hi
The file you have requested
(http://www.cs.york.ac.uk/fp/cpphs-1.5-win32.zip) could not
be found on this server.
The slightly older version works:
http://www.cs.york.ac.uk/fp/cpphs-1.2-win32.zip
I'm unable to get SSH from this machine, so can't tell where that file
has gone to. Malcolm
Hi
In future questions like this are usually best directed to
haskell-cafe, with haskell being left for annoucements.
The standard full haskell representation is in Template Haskell
(http://haskell.org/ghc/docs/latest/html/libraries/template-haskell/Language-Haskell-TH.html).
If you want to work
Hi
Then, I set out to learn Monads + Category Theory from a Math
perspective.
This is where you went wrong. I know none of this stuff and am
perfectly happy with IO in Haskell. Read
http://www.haskell.org/haskellwiki/Monads_as_Containers and then read
lots of other Monad tutorials for Haskell.
Hi
main n = print . sum . map read . take n . reverse . lines = getContents
Could someone describe succinctly how to compute the space complexity of
this program, if there are m lines of input and m n? Many thanks. --PR
The space complexity is the size of the file - i.e. of size m. reverse
Hi
(/ 10) means the function that divides its argument by 10
(- 10) however is just the number -10, even if I put a space between the -
and 10.
How can I create a function that subtracts 10 from its argument in a clean
way then?
subtract is the way to go. (`subtract` 10)
I think you
Hi
I think you should have to write negative numbers using the syntax
0-10, since currently having one single unary operator is ugly.
I think writing 0-10 is ugly.
Ugly - yes. But very clear as to its meaning. How often do people
actually write negative numeric literals? My guess is that
Hi
I agree. = 1.0 isn't viable in the long term. Rather, a specific list,
or bounded range of tested versions seems likely to be more robust.
In general, if it compiles and type checks, it will work. It is rare
that an interface stays sufficiently similar that the thing compiles,
but then
Hi
In general, if it compiles and type checks, it will work. It is rare
that an interface stays sufficiently similar that the thing compiles,
but then crashes at runtime. Given that, shouldn't the tested versions
be something a machine figures out - rather than something each
library
Hi
We certainly need a function to split a list into sections. Whether it
be wordsBy, or something like linesBy, or some new split variant.
wordsBy :: (a - Bool) - [a] - [[a]]
wordsBy p s = case dropWhile p s of
[] - []
s':rest - (s':w) : wordsBy p s''
where (w, s'')
Hi Ketil,
I'm struggling to get my HXT-based parser to parse a largish file
(300MB), even after breaking into reasonably-sized chunks. The
culprit appears to be parsing one element comprising 25K lines of
text, which apparently requires more memory than the 2Gb my computer
is equipped with.
Hi
You are still over by one test. Try instead:
wordsBy :: (a - Bool) - [a] - [[a]]
wordsBy p s = case dropWhile p s of
[] - []
s':rest - (s':w) : wordsBy p (drop 1 s'')
where (w, s'') = break p rest
This still has the redundant empty list tests,
Perhaps.
Hi
If you want to guarantee that level of optimization,
you probably have to inline everything by hand
and not use any library functions at all. I wonder how
much of that is already done by the compiler,
though.
A reasonable level of optimisation for this function would be that the
Hi
I can see problems with this. This comes up when typing windows file path's:
C:\path to my\directory\boo
If this now reports no errors, who wants to guess which come up as
escape codes, and which don't. The way other languages like C# have
dealt with this is by introducing a new type of
Hi Bill,
In the Haskell libraries, is there an OS abstraction module, that would
hide the POSIX API and Win-32 API? If not, this would be nice so that
Haskell programs could be written in an OS independent manner!
Yes, Haskell provides a fairly complete API in the base libraries,
which
module to manipulate filepaths, if you are doing that
to any great extent.
If you say what you are tying to do, and why you suspect it might not
just work in a cross platform manner, people might be able to
address your specific concerns.
Thanks
Neil
On 10/22/07, Neil Mitchell [EMAIL PROTECTED
Hi Bill
I am really talking about a module or perhaps a Haskell class that
provides notion for multiple threads of execution, semaphores, .. that
hides POSIX vs Win32 APIs .. i.e. the underlying OS APIs would be totally
hidden.
I think you are thinking in a C way. In Haskell, portable is
Hi Bill,
I am really talking about a module or perhaps a Haskell class that
provides notion for multiple threads of execution, semaphores, .. that
hides POSIX vs Win32 APIs .. i.e. the underlying OS APIs would be
totally
hidden.
I think you are thinking in a C way. In
Hi
Are there binary constants in Haskell, as
we have, for instance, 0o232 for octal and
0xD29A for hexadecimal?
No, though it is an interesting idea.
You can get pretty close with existing Haskell though:
(bin 100010011)
where bin :: Integer - Integer, and is left as an exercise for
Hi
I've been working on optimising Haskell for a little while
(http://www-users.cs.york.ac.uk/~ndm/supero/), so here are my thoughts
on this. The Clean and Haskell languages both reduce to pretty much
the same Core language, with pretty much the same type system, once
you get down to it - so I
Hi
So in a few years time when GHC has matured we can expect performance to be
on par with current Clean? So Clean is a good approximation to peak
performance?
No. The performance of many real world programs could be twice as fast
at least, I'm relatively sure. Clean is a good short term
Hi
I don't think the register allocater is being rewritten so much as it is
being written:
From talking to Ben, who rewrote the register allocator over the
summer, he said that the new graph based register allocator is pretty
good. The thing that is holding it back is the CPS conversion bit,
Hi
The binaries are ~47MiB apiece. I suspect that almost everyone on
Windows and Linux x86 will want the binaries too, since compiling GHC
tends to take a while. Anyway, it seems like haskell.org is becoming
more responsive now, but it would be something to keep in mind for the
future.
Hi Mike,
It looks as if hoogle isn't working. I get 404s whenever I try to do any
search on hoogle.
Hoogle works for performing searches, but the documentation links are
incorrect. Expect this fixed by this evening!
Thanks
Neil
___
Haskell-Cafe
Hi Mike,
It looks as if hoogle isn't working. I get 404s whenever I try to do any
search on hoogle.
I have fixed quite a lot of the links, some will still be broken, but
hopefully not too many. Really, hoogle needs upgrading to use the new
base library etc - I'll try and do that sometime
Hi Arthur,
The correct steps to take are:
1) install GHC from the windows installer - trivial
2) install Gtk2hs from the windows installer
Unfortunately Gtk2hs hasn't been updated to work with GHC 6.8.1, so
step 2 will fail. The person who is going to do this is Duncan. He
usually breaks down
Hi
I've written a little Haskell program to get information from a MySQL
database (great thanks to anybody reading this who works on HSQL, by
the way) but I want to keep the user's password concealed, obviously.
Currently I prompt for it from the terminal, but the problem is that
it's echoed
Hi
The final alternative is that I just call MD5SUM.EXE from my Haskell
program and try to parse the output. But that strikes me as rather messy.
Messy, but I don't see any disadvantage to doing it this way - if you
can control that the MD5SUM program is installed alongside your code.
Of
Hi
The MD5SUM.EXE file I have chokes if you ask it to hash a file in
another directory. It will hash from stdin, or from a file in the
current directory, but point-blank refuses to hash anything else.
Try http://www.cs.york.ac.uk/fp/yhc/dependencies/UnxUtils.zip - that
has an MD5SUM program
Hi
Is there anyway to cut down this code and to not use auxillary functons,
but instead use pattern matching?
You haven't attached any code, but even if you had, I don't think it
would have worked.
[hi ryan 1,hi jeff 2] becomes [[hi,ryan 1], [hi,jeff, 2]].
In Haskell lists are collections
Hi
...if GHC is written in Haskell, how the heck did they compile GHC in
the first place?
GHC was not the first Haskell compiler, hbc was the main compiler at
some point, so I suspect they used hbc. There was also lazy ML which I
suspect was used to bootstrap hbc - but I'm not sure of the
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