[Haskell-cafe] Feature Proposal: GHC Flag for implicit external Prelude

[Edward Kmett]

Personally I put all the flags in each file. That way I can know what
features I'm needing at each use-site. Most of my files have only 1-2
flags. Others have 30.

It is important to me to know where I'm leaning on things like
FlexibleInstances that can make inference for users worse if I don't do so
carefully.

It also lets me load up individual modules as I'm working from ghci
directly rather than rebuild the entire package.

This is, of course, a matter of style, so tastes vary.

-Edward


On Tue, Jul 15, 2014 at 2:34 PM, Bardur Arantsson <spam at scientician.net>
wrote:

> On 2014-07-15 19:30, Michael Orlitzky wrote:
> > On 07/14/2014 11:23 PM, Andrew Gibiansky wrote:
> >> Hey all,
> >>
> >> I would like to propose a very minor flag to add to GHC. I would like
> >> GHC to have a --with-prelude flag, which would specify an alternate
> >> Prelude to use instead of the default Haskell prelude.
> >>
> >> This would have an effect similar to -XNoImplicitPrelude and an
> additional
> >>
> >> import MyNewPrelude
> >>
> >> in the source file. It might be a /little/ different semantically, as a
> >> qualified import would disable the original implicit import, just like
> >> it does with the default Haskell prelude.
> >>
> >
> [--snip--]
> >
> > We went down this road once before with -fglasgow-exts. Eventually, we
> > all realized it was much better to place the required extensions in
> > pragmas at the top of the file.
> >
>
> Except "we" don't :). "We" use flags in the .cabal file. Or, at least I
> do. Explicitness certainly sometimes has great value, but not always.
>
> Regards,
>
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