[Haskell-cafe] Re: [Haskell] ANN: ghci-haskeline 0.1

[Judah Jacobson]

On Tue, Jan 13, 2009 at 6:03 AM, Mauricio <briqueabraque at yahoo.com> wrote:
>>> Haskeline is designed to remove the readline dependency, because Windows
>>> does not have readline.  So rlwrap is useless there.
>>>
>>
>> Ah, I hadn't considered Windows support--that makes sense.  Thanks,
>> that answers my questions.
>>
>> AHH
>
> One nice thing would be to write something like rlwrap
> that would work everywhere Haskell does. Even more
> sofisticated behavior could come from some comunication
> from the api, using standard OS facilities (like a file
> with an updated list of completions, or something more
> clever).
>
> (For those interested: rlwrap is available in cygwin.
> It used to work very well on old ghci, when line
> editing wasn't available.)

This does sound useful; the main difficulty is that when a program has
stdin piped from another process it may behaved differently.  For
example, ghci uses block buffering and doesn't print its prompt when
stdin doesn't appear to be a terminal.  The solution on POSIX is
probably to use some sort of pseudo-terminal support; I don't know
what the right thing to do on Windows is.

The following post discusses those issues in a little more detail:
http://www.haskell.org/pipermail/haskell-cafe/2008-May/042342.html

-Judah