Difference between revisions of "UTF-8"

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(whoops, reuse the same example, why don't we)
m (Reverted edits by Tomjaguarpaw (talk) to last revision by PhilipNeustrom)
 
(4 intermediate revisions by 3 users not shown)
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provides a drop-in replacement for System.IO
 
provides a drop-in replacement for System.IO
   
== Example ==
 
  +
''What about other string encodings?''
   
This example reverses every line in a file (saving the results in the file + ".rev")
 
 
== Example ==
 
 
If we use a function from System.IO.UTF8, we should also hide the equivalent one from the Prelude. (Alternatively, we could import the UTF8 module qualified)
If we use a function from <code>System.IO.UTF8</code>, we should also hide the equivalent one from the Prelude. (Alternatively, we could import the UTF8 module qualified)
 
   
 
<haskell>
 
<haskell>
 
> import System.IO.UTF8
 
> import System.IO.UTF8
> import Prelude hiding (readFile)
+
> import Prelude hiding (readFile, writeFile)
  +
> import System.Environment (getArgs)
 
</haskell>
 
</haskell>
  +
  +
The readFile and writeFile functions are the same as before...
   
 
<haskell>
 
<haskell>
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> do args <- getArgs
 
> do args <- getArgs
 
> mapM_ reverseUTF8File args
 
> mapM_ reverseUTF8File args
 
  +
 
> reverseUTF8File :: FilePath -> IO ()
 
> reverseUTF8File :: FilePath -> IO ()
 
> reverseUTF8File f =
 
> reverseUTF8File f =
> do f <- readFile f
+
> do c <- readFile f
> writeFile (f ++ ".rev) $ reverseLines f
+
> writeFile (f ++ ".rev") $ reverseLines c
 
> where
 
> where
 
> reverseLines = unlines . map reverse . lines
 
> reverseLines = unlines . map reverse . lines
<haskell></haskell>
+
</haskell>

Latest revision as of 15:20, 6 February 2021


The simplest solution seems to be to use the utf8-string package from Galois. It provides a drop-in replacement for System.IO

What about other string encodings?

Example

If we use a function from System.IO.UTF8, we should also hide the equivalent one from the Prelude. (Alternatively, we could import the UTF8 module qualified)

> import System.IO.UTF8
> import Prelude hiding (readFile, writeFile)
> import System.Environment (getArgs)

The readFile and writeFile functions are the same as before...

> main :: IO ()
> main =
>  do args <- getArgs
>     mapM_ reverseUTF8File args

> reverseUTF8File :: FilePath -> IO ()
> reverseUTF8File f =
>   do c <- readFile f
>      writeFile (f ++ ".rev") $ reverseLines c
>   where
>     reverseLines = unlines . map reverse . lines