Readline read_history and write_history addition

Judah Jacobson judah.jacobson at
Wed Feb 20 20:31:06 EST 2008

Hi all,

Discussion over this issue has died down.  Yitzchak and others have
made good arguments for the type signatures

readHistory :: String -> IO Bool
writeHistory :: String -> IO Bool

which reflect the non-exceptional nature of failure of those functions.

Does anyone have any problems with implementing the following patch
from Alex (along with the above change)?

For reference, this is in relation to the following proposal:

If no objections are raised by next week (say, Feb. 27), we should
make the above changes to readline, which will let us implement #2050
(persistent history file in ghci).


On Wed, Feb 6, 2008 at 1:09 PM, Yitzchak Gale <gale at> wrote:
> Judah Jacobson wrote:
>  > - readFile... writeFile...
> > I think of readHistory and writeHistory as analogues to the above
>  > functions.
>  I don't think so. I don't really care about the file itself - that
>  just happens to be the way readline implements its persistence.
>  Non-existence of the file is the normal way that readline
>  represents the fact that there isn't any history yet.
>  The semantics of the API call are: load history, if any exists yet,
>  and report the result. Nothing exceptional about that.
>  > All that being said, this is a relatively minor issue
>  Agreed. All the more so with the MonadIO problem now factored
>  out.
>  Regards,
>  Yitz

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