[Haskell-cafe] Example code won't compile
Why won't this code compile?
Michael
===
{- Author: Jeff Newbern
Maintainer: Jeff Newbern jnewb...@nomaware.com
Time-stamp: Thu Aug 14 09:53:53 2003
License: GPL
-}
{- DESCRIPTION
Example 14 - Using the IO monad
Usage: Compile the code to produce a poor replacement for
the standard Unix tr command.
Try: cat file | ./ex14 aeiou X
cat file | ./ex14 _
./ex14 abc
-}
import Monad
import System
import IO
import Control.Monad.Error
-- translate char in set1 to corresponding char in set2
translate :: String - String - Char - Char
translate [] _ c = c
translate (x:xs) [] c = if x == c then ' ' else translate xs [] c
translate (x:xs) [y] c = if x == c then y else translate xs [y] c
translate (x:xs) (y:ys) c = if x == c then y else translate xs ys c
-- translate an entire string
translateString :: String - String - String - String
translateString set1 set2 str = map (translate set1 set2) str
usage :: IOError - IO ()
usage e = do putStrLn Usage: ex14 set1 set2
putStrLn Translates characters in set1 on stdin to the
corresponding
putStrLn characters from set2 and writes the translation to
stdout.
-- translates stdin to stdout based on commandline arguments
main :: IO ()
main = (do [set1,set2] - getArgs
contents - hGetContents stdin
putStr $ translateString set1 set2 contents)
`catchError` usage
-- END OF FILE
=
[mich...@localhost ~]$ ghc ex14.hs -o ex14
ex14.o: In function `rF8_info':
(.text+0x48): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziError_zdf17_closure'
ex14.o: In function `sGp_info':
(.text+0x861): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziError_zdf17_closure'
ex14.o: In function `sGp_info':
(.text+0x91d): undefined reference to
`__stginit_mtlzm1zi1zi0zi2_ControlziMonadziError_'
ex14.o: In function `rF8_info':
(.text+0x50): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziErrorziClass_zdp1MonadError_info'
ex14.o: In function `sGp_info':
(.text+0x869): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziErrorziClass_catchError_info'
ex14.o: In function `rF8_srt':
(.data+0x0): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziError_zdf17_closure'
ex14.o: In function `Main_main_srt':
(.data+0x6c): undefined reference to
`mtlzm1zi1zi0zi2_ControlziMonadziError_zdf17_closure'
collect2: ld returned 1 exit status
[mich...@localhost ~]$
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Re: [Haskell-cafe] Example code won't compile
nowgate: Why won't this code compile? [mich...@localhost ~]$ ghc ex14.hs -o ex14 Missing --make I'd also add -O2, but I'm like that. -- Don ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Example code won't compile
This example compiles fine without --make. What's the difference?
Michael
==
{- Author: Jeff Newbern
Maintainer: Jeff Newbern jnewb...@nomaware.com
Time-stamp: Wed Jul 2 18:11:36 2003
License: GPL
-}
{- DESCRIPTION
Example 13 - Using the List monad
Usage: Compile the code and execute the resulting program
with various arguments. Each argument will produce
a list of possible parses of the argument as a decimal
number, a hexadecimal number or a word.
Try: ./ex13 34 f3 bean
./ex13 food f00d
./ex13 beef 10 n!
./ex13 why? (punctuation)
-}
import Monad
import System
import Char
-- we can parse three different types of terms
data Parsed = Digit Integer | Hex Integer | Word String deriving Show
-- attempts to add a character to the parsed representation of a hex digit
parseHexDigit :: Parsed - Char - [Parsed]
parseHexDigit (Hex n) c = if isHexDigit c then
return (Hex ((n*16) + (toInteger (digitToInt c
else
mzero
parseHexDigit _ _ = mzero
-- attempts to add a character to the parsed representation of a decimal digit
parseDigit :: Parsed - Char - [Parsed]
parseDigit (Digit n) c = if isDigit c then
return (Digit ((n*10) + (toInteger (digitToInt c
else
mzero
parseDigit _ _ = mzero
-- attempts to add a character to the parsed representation of a word
parseWord :: Parsed - Char - [Parsed]
parseWord (Word s) c = if isAlpha c then
return (Word (s ++ [c]))
else
mzero
parseWord _ _ = mzero
-- tries to parse the digit as a hex value, a decimal value and a word
-- the result is a list of possible parses
parse :: Parsed - Char - [Parsed]
parse p c = (parseHexDigit p c) `mplus` (parseDigit p c) `mplus` (parseWord p c)
-- parse an entire String and return a list of the possible parsed values
parseArg :: String - [Parsed]
parseArg s = do init - (return (Hex 0)) `mplus` (return (Digit 0)) `mplus`
(return (Word ))
foldM parse init s
-- show the original string and all possible parses for the string
showResult :: String - IO ()
showResult s = do putStr s
putStr :
print (parseArg s)
-- prints possible parsed values for command-line arguments
main :: IO ()
main = do args - getArgs
mapM_ showResult args
-- END OF FILE
--- On Fri, 5/15/09, Lennart Augustsson lennart.augusts...@gmail.com wrote:
From: Lennart Augustsson lennart.augusts...@gmail.com
Subject: Re: [Haskell-cafe] Example code won't compile
To: michael rice nowg...@yahoo.com
Cc: haskell-cafe@haskell.org haskell-cafe@haskell.org
Date: Friday, May 15, 2009, 7:25 PM
--make
-- Lennart (iPhone)
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Re: [Haskell-cafe] Example code won't compile
The one important line is import Control.Monad.Error It adds dependancy on mtl package, which is not used by default (contrary to 'base' package, which includes Monad, System and IO modules). With --make GHC adds it automatically. Therefore $ ghc -package mtl ex14.hs compiles fine. I'd recommend using --make. In rare occasions when there is a namespace clash between packages one can simply hide offending packages or specify preferred ones. Best regards Christopher Skrzętnicki ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Example code won't compile
OK. Thanks, everyone. Michael --- On Fri, 5/15/09, Krzysztof Skrzętnicki gte...@gmail.com wrote: From: Krzysztof Skrzętnicki gte...@gmail.com Subject: Re: [Haskell-cafe] Example code won't compile To: michael rice nowg...@yahoo.com Cc: Lennart Augustsson lennart.augusts...@gmail.com, haskell-cafe@haskell.org haskell-cafe@haskell.org Date: Friday, May 15, 2009, 9:55 PM The one important line is import Control.Monad.Error It adds dependancy on mtl package, which is not used by default (contrary to 'base' package, which includes Monad, System and IO modules). With --make GHC adds it automatically. Therefore $ ghc -package mtl ex14.hs compiles fine. I'd recommend using --make. In rare occasions when there is a namespace clash between packages one can simply hide offending packages or specify preferred ones. Best regards Christopher Skrzętnicki ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
