FORTRAN and HASKELL
Somebody works with together FORTRAN and Haskell. Exists some funcao to transform codigo FORTRAN into codigo HASKELL? Thanks, Allan Bruno __ AcessoBOL, só R$ 9,90! O menor preço do mercado! Assine já! http://www.bol.com.br/acessobol ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: FORTRAN and HASKELL
--- clusterpoli [EMAIL PROTECTED] wrote: Somebody works with together FORTRAN and Haskell. Exists some funcao to transform codigo FORTRAN into codigo HASKELL? TXL might help, but it's its own functional language. It can probably convert FORTRAN to Haskell given the EBNF for each language, but I'm not sure how it works... http://www.research.avayalabs.com/user/wadler/realworld/ls2000.html http://gatekeeper.dec.com/pub/misc/txl/ Otherwise, I would look at what algorithm the FORTRAN is implementing, the either write it in Haskell, or look for it on the Internet using http://www.google.com/ For example: http://www.cs.chalmers.se/pub/haskell/library/ http://www.cs.chalmers.se/pub/haskell/library/bevan/index __ Do You Yahoo!? Yahoo! GeoCities - quick and easy web site hosting, just $8.95/month. http://geocities.yahoo.com/ps/info1 ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
RE: IO errors
A quick look at the source looks like both GHC and NHC will simply pass on errors from the OS, so for example with module Main where import IO import Directory main :: IO() main = do catch (createDirectory this/does/not/exist/foo) (\e - putStrLn $ show $ map (flip ($) e) errors) errors :: [(IOError - Bool)] errors = [isDoesNotExistError, isIllegalOperation, isPermissionError, isAlreadyExistsError] both GHC and NHC give [True,False,False,False] (I don't seem to have a hugs Directory.hs) while the library report only allows isIllegalOperation, isPermissionError and isAlreadyExistsError. I haven't looked for other cases of this. Two possibilities: either createDirectory should act like 'mkdir -p' and make the whole path, or the library report should document isDoesNotExistError as a possible error thrown by createDirectory. I'd vote for the latter. No doubt there are many other cases of this, we should really do a full audit of the I/O library specs. Cheers, Simon ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
RE: IO errors
| Two possibilities: either createDirectory should act like | 'mkdir -p' and make the whole path, or the library report | should document isDoesNotExistError as a possible error | thrown by createDirectory. I'd vote for the latter. I'm willing to do that for H98 unless anyone can think of a reason I shouln't. Simon ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
RE: Possible bug/omission in Numeric library?
| However, I would guess that changing the type signature of
| the current showInt function is unacceptable for Haskell'98.
| Maybe we should consider adding the more general version
| under a new name like showIntBase, together with
| show{Dec,Oct,Hex}? This would break no existing code, and
| clear up the slight anomaly in the current capability of the
| Haskell'98 library.
Hmm. This is another unforced change, but admittedly to the libraries,
which have received much less attention and in some cases (like
this) look more accidental than deliberate. So I've been using a lower
bar for modifications to the Libraries than to the Report.
As you say, we can't change the type of showInt. I suppose we could
add:
showIntAtBase :: Integral a
= a-- base
- (a - Char) -- digit to char
- a-- number to show.
- ShowS
showOct, showHex :: Integral a = a - ShowS
Q1: But would we really want showDec too?
Identical to existing showInt?
I am disinclined to use K-F's extra generality for H98, nice though it
is.
Too different from readInt.
Also, GHC's NumExts has
doubleToFloat :: Double - Float
floatToDouble :: Float - Double
Q2: If we are going to run round adding functions to
Numeric, should we add those too? It's hard to know
where to stop... but if that conversion is what you want to
do, H98 doesn't give a good way to do it.
Simon
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Global variables
Hello, I am interested in using global variables (in GHC). I need a variable to store list of Integers to store temporary results. I have been reading the module MVar, but I wonder if there is an alternative way of doing it. I have already implemented my function using an auxiliar argument where I put my lists of Integers. Will the use of a global variable improve my function? Thanks in advance, J. Ignacio ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Possible bug/omission in Numeric library?
As you say, we can't change the type of showInt. I suppose we could add: showIntAtBase :: Integral a=20 =3D a-- base - (a - Char) -- digit to char - a-- number to show. - ShowS showOct, showHex :: Integral a =3D a - ShowS Q1: But would we really want showDec too? Identical to existing showInt? I only suggested it for consistency of naming. However, since showInt is not the dual of readInt, we can't have consistency anyway. Regards, Malcolm ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Global variables
JIGG alternative way of doing it. I have already implemented my function JIGG using an auxiliar argument where I put my lists of Integers. Will JIGG the use of a global variable improve my function? There is no such thing as mutable variable (as in imperative languages) in Haskell (and my guess is that you are looking exactly for that type), so I guess that for now you must bear with aux. parameter. Use of state monad will help to improve the look of your function, but learning curve for monads could be steep. -- Dmitry Astapov //ADEpt E-mail: [EMAIL PROTECTED] GPG KeyID/fprint: F5D7639D/CA36 E6C4 815D 434D 0498 2B08 7867 4860 F5D7 639D ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Confused about Random
With the following module: module Main where import Random data Foo = Foo StdGen main :: IO() main = do let rs = randoms (Foo (mkStdGen 39)) :: [Int] rRs = randomRs (0,9) (Foo (mkStdGen 39)) :: [Int] putStrLn $ show $ take 100 rs putStrLn $ show $ take 100 rRs instance RandomGen Foo where genRange _ = (0, 1) next (Foo g) = (val `mod` 2, Foo g') where (val, g') = random g split _ = error Not implemented ghc gives me [-2147476078,7482,-2147476078,-2147476078,-2147476079,-2147476078,7483,7482,7482,-2147476079,-2147476078,-2147476079,-2147476079,7482,-2147476078,-2147476078,-2147476078,-2147476079,7482,7483,7482,7483,7482,-2147476078,-2147476078,-2147476078,7483,-2147476079,7482,-2147476078,-2147476079,-2147476078,7483,-2147476079,7483,7482,-2147476079,7483,7482,7483,-2147476078,-2147476079,-2147476079,7482,-2147476078,7482,-2147476079,-2147476079,7482,-2147476078,7483,7483,-2147476079,-2147476078,7483,7483,-2147476078,-2147476079,-2147476078,-2147476079,-2147476078,7483,7483,7482,7482,7483,-2147476078,-2147476079,-2147476079,7482,7483,-2147476078,-2147476079,-2147476079,-2147476078,7482,7483,-2147476079,7482,7482,7482,7483,-2147476079,-2147476079,-2147476078,7482,7482,7482,7482,-2147476079,7482,7482,-2147476079,7483,-2147476078,7482,7483,-2147476079,-2147476079,7482] [1,2,2,1,1,2,1,2,1,1,1,2,2,2,2,1,2,1,1,1,1,2,1,1,1,1,2,1,1,2,1,2,1,2,1,1,2,1,2,2,2,1,2,2,2,1,1,2,1,2,1,2,2,2,1,1,2,1,1,2,1,1,1,2,2,2,1,1,2,2,2,1,1,1,2,2,2,1,2,2,1,2,1,1,1,1,2,1,1,2,2,1,1,1,1,1,2,1,1,2] The first list doesn't seem to cover the whole spectrum and I was expecting the second list to be composed over 0s through 9s. Is my understanding wrong? nhc complains Context for Random.Random needed in left hand pattern at 17:11. and hugs doesn't seem to know genRange exists. With it commented out it returns the same as ghc. Thanks Ian ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Possible bug/omission in Numeric library?
Also, GHC's NumExts has doubleToFloat :: Double - Float floatToDouble :: Float - Double Q2: If we are going to run round adding functions to Numeric, should we add those too? It's hard to know where to stop... but if that conversion is what you want to do, H98 doesn't give a good way to do it. Haskell already has fromRealFrac which does the same job (ignoring NaNs, -0, etc.). AFAIK, the only reason you'd use these shortcuts is if you're using a compiler that can't optimize fromRealFrac (i.e., you're not using HBC or GHC) or exploring the limits of Haskell's support for IEEE arithmetic. My feeling is that this is something of an unforced change. Adding functions can break code (though the fix is easy) so, whilst I agree that the bar is lower for libraries and for adding functions, I think we should still exercise some restraint. This is especially true since it's not clear that this is the right thing to do (since we have fromRealFrac already) and it is hard to remove features once you've added them. -- Alastair Reid[EMAIL PROTECTED]http://www.cs.utah.edu/~reid/ ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Global variables
Hello, I am interested in using global variables (in GHC). I need a variable to store list of Integers to store temporary results. I have been reading the module MVar, but I wonder if there is an alternative way of doing it. I have already implemented my function using an auxiliar argument where I put my lists of Integers. Will the use of a global variable improve my function? There's many ways to achieve the same goals as C programmers achieve using mutable (global) variables including using laziness, use of accumulator arguments, and, supported by most compilers but not standard Haskell, mutable variables. (Unlearning imperative programming habits is one of the big challenges in learning Haskell.) Since there are so many ways to avoid mutable variables and (many less) circumstances where mutable variables are the best solution, it's hard to give useful advice without more information about the problem. -- Alastair Reid[EMAIL PROTECTED]http://www.cs.utah.edu/~reid/ ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Where to ask questions regarding categories and datatypes
Peter Douglass writes: Hi, I have a number of questions regarding categories and datatypes. I know that many of the folk in this mailing list could answer these question, but I wonder if there is a more appropriate forum. (i.e. the question are not Haskell specific). Why don't you try the Types Forum [EMAIL PROTECTED] See also http://www.cis.upenn.edu/~bcpierce/types/ Or, if your questions are more on the categories side, there is also: Categories List The category theory mailing list, moderated by Bob Rosebrugh. http://www.mta.ca/~cat-dist/ Claus ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Global variables
Hello, I am interested in using global variables (in GHC). I need a variable to store list of Integers to store temporary results. I have been reading the module MVar, but I wonder if there is an alternative way of doing it. I have already implemented my function using an auxiliar argument where I put my lists of Integers. Will the use of a global variable improve my function? no!-) ah, well, perhaps.. As you've already got your function, using auxiliary arguments, you probably don't really need to re-write it in a less functional style. But you will have noticed that much of your code repeatedly does the same thing - passing the auxiliary around. It's good functional programming practice to abstract away repeated code (both for reuse and to get more concise code). One way to do that will lead you into monads (your function is a state transformer, transforming the state of the auxiliary list at each step), still a functional solution. If you really, and absolutely want and must use global, mutable variables in a functional language, you might find a recent paper by John Hughes helpful, on that very topic. See his home page: http://www.cs.chalmers.se/~rjmh/ Hth, Claus ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Global variables
At 2001-11-29 05:31, Juan Ignacio García García wrote: I am interested in using global variables (in GHC). In JVM-Bridge (nearly there!) I use lifted monads to store global constants, though variables are not hard either. This does mean an extra function needed to call IO functions, but in my case you'd be calling mostly my glue functions to Java code, which are in the lifted monad anyway. Lifted monads look something like this: data MyAction a = MkMyAction ((consts,vars) - (vars,a)); instance Monad MyAction where etc. I actually have a class for monads that lift the IO monad: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/~checkout~/jvm-bridge/sourc e/Haskell/IOLiftedMonad.hs?rev=HEADcontent-type=text/plain -- Ashley Yakeley, Seattle WA ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Re: Global variables
At 2001-11-29 11:13, Ashley Yakeley wrote: Lifted monads look something like this: data MyAction a = MkMyAction ((consts,vars) - (vars,a)); instance Monad MyAction where etc. Whoops, should be data MyAction a = MkMyAction ((consts,vars) - IO (vars,a)); -- Ashley Yakeley, Seattle WA ___ Haskell mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell
Strictness making it worst?
Hi, I've just started messing around with strictness. My goal now is understanding when and how to use it. I began with simple examples like making a strict foldl. When trying to sum a list of 6 elements with lazy foldl I'd get a stack space overflow, with a strict foldl I was able to sum a list of 1E8 elements :) Then I thought I'd mess with the fibonnaci function. I began with: fibac :: IntPos - (IntPos,IntPos) - (IntPos,IntPos) fibac n (a,b) | n == 0= (a,b) | otherwise = fibac (n-1) (b,a+b) Then I tried: sfibac :: IntPos - (IntPos,IntPos) - (IntPos,IntPos) sfibac n (a,b) | n == 0= (a,b) | otherwise = sfibac (n-1) (b, (+b) $! a) I tried both functions with ghc 5.00.1 The strict version was not only slower, but I'd get stack overflows for numbers that worked with the 1st version!! (like 10) I expect sfibac and fibac work this way: assuming that a+b = c b+c = d c+d = e sfibac: sfibac 4 (a, b) - sfibac 3 (b, a+b) - sfibac 2 (a+b, b+(a+b)) - sfibac 1 (b+(a+b), (a+b)+(b+(a+b))) - sfibac 0 ((a+b)+(b+(a+b)), (b+(a+b)) + (a+b)+(b+(a+b))) now if I had to evaluate the first element I'd get (a+b)+(b+(a+b)) - c+(b+c) - c+d - e fibac: sfibac 4 (a, b) - sfibac 3 (b, a+b) - sfibac 2 (c, b+c) - sfibac 1 (d, c+d) - sfibac 0 (e, d+e) I'd expect sfibac to be faster, but what I find even more strange is the stack space overflow in sfibac! why? Greetings, J.A. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: Strictness making it worst?
Then I tried: sfibac :: IntPos - (IntPos,IntPos) - (IntPos,IntPos) sfibac n (a,b) | n == 0= (a,b) | otherwise = sfibac (n-1) (b, (+b) $! a) I'm sorry I meant: sfibac :: IntPos - (IntPos,IntPos) - (IntPos,IntPos) sfibac n (a,b) | n == 0= (a,b) | otherwise = sfibac (n-1) (b, (a+) $! b) otherwise the reductions would be wrong fibac: sfibac 4 (a, b) - sfibac 3 (b, a+b) - sfibac 2 (c, b+c) - sfibac 1 (d, c+d) - sfibac 0 (e, d+e) In fact I would expect that using ((a+) $! b) would be better than (b, (+b) $! a), but the 1st seemed to be the worst in terms of both speed and stack space problems. J.A. ___ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe
