Ahn, Ki Yung wrote:
Judah Jacobson wrote:
With this release, thanks to much appreciated feedback and suggestions
from the
community, Haskeline's features become more competitive with its C
alternatives. Improvements include:
* A multitude of new emacs and vi bindings:
http://trac.haskell.org/haskeline/wiki/KeyBindings
* A new preference 'historyDuplicates' to remove repeated history
entries
* Recognize PageUp and PageDown keys
* Compatibility with ghc-6.12
* Correct width calculations for Unicode combining characters
Oh, this Unicode width calculation sounds great! This was the only
reason I needed readline and stay away from haskline. If this works
properly, I no more nead to depend on readline for line input. I think
this is a very good news for any mutibyte charset users. I'll try to
replace readline in my memscript utility to haskline and come back to
report the results. Thanks for your work on this!
Sorry for the bad news, but haskeline does not caculate correct width
for Korean, and I don't believe it will for Chinese or Japanese either.
My linux LANG setting LANG=ko_KR.UTF-8, and I tested with the following
example program in the Hackage Haddock documentation:
> import System.Console.Haskeline
>
> main :: IO ()
> main = runInputT defaultSettings loop
> where
> loop :: InputT IO ()
> loop = do
> minput <- getInputLine "% "
> case minput of
> Nothing -> return ()
> Just "quit" -> return ()
> Just input -> do outputStrLn $ "Input was: " ++ input
> loop
When I typed in Korean characters and tried to erase them with backspace
or del, it only deletes half of the characters on the screen although it
seems that in the buffer the composed multibyte character was deleted.
That is, when I type three Korean characters of my name, which is of 6
ASCII alphabet character width, and press backspace key three times, the
buffer is empty, but on my screen there is one and a half character
remaining.
This same problem existed in the previous versions as well, and this is
why multibyte charset users cannot adopt haskeline for their project,
and have less satisfying experience using ghci to testing text input
output actions.
In summary, I think haskeline is calculating the correct width but only
applies that to the buffer content but not what is printed on the
screen. This gives the user very awkward experience when they try to
move the cursor back to fix the line input.
Ahn, Ki Yung
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