Hi Duncan,
> > That is interesting. I'd be interested in how exactly that works. Is
> > there a place where I can read about it? Or if not, can you point me to
> > the related commits?
>
> http://lambdasandwich.blogspot.co.uk/2011/08/ending-gsoc.html
>
> For the changes to ghci see the ghc git repo. Look for stuff related
> to .ghci file handling. That was the main extension needed, so we could
> specify a .ghci file on the command line.
Thanks a lot for the pointers.
I looked at [1] (specifically at mkDotGhci), but as far as I can tell
this does not work anymore.
Here is what I tried:
ghci> :def! foo (\_ -> return "23")
ghci> :foo
23
ghci> :def! reload (\_ -> return "23")
ghci> :reload
Ok, modules loaded: none.
It seems that builtins always take precedence over user defined
commands. I tried this with GHC 7.2.2, GHC 7.4.2 and GHC 7.6.1.
It works with GHC 7.0.4. But even here the code has issues, because it
does an :undef so that it can call the original :reload. But after that
our custom :reload is gone. So it works, but only once. This is easily
fixed, e.g. the following works with GHC 7.0.4:
ghci> :def! __reload__ (\_ -> return ":!echo
'do-cabal-specific-stuff'\n:undef reload\n:reload\n:def reload (\\_ -> return
\":__reload__\")")
ghci> :def! reload (\_ -> return ":__reload__")
ghci> :reload
do-cabal-specific-stuff
Ok, modules loaded: none.
ghci> :reload
do-cabal-specific-stuff
Ok, modules loaded: none.
I think if we want to redefine :reload we need the :def semantics we had
in GHC 7.0.4. Should I open a GHC ticket?
Cheers,
Simon
[1]
http://code.haskell.org/~bogiebro/cabal/cabal/cabal/Distribution/Simple/GHC.hs
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