Ben Gamari <b...@smart-cactus.org> writes:
> This is a fair point that comes up fairly often. The fact that CPP is
> required to silence redundant import warnings is quite unfortunate.
> Others languages have better stories in this area. One example is Rust,
> which has a quite flexible `#[allow(...)]` pragma which can be used to
> acknowledge and silence a wide variety of warnings and lints [1].
>
> I can think of a few ways (some better than others) how we might
> introduce a similar idea for import redundancy checks in Haskell,
>
> 1. Attach a `{-# ALLOW redundant_import #-}` pragma to a definition,
...
> 2. Or alternatively we could make this a idea a bit more precise,
> {-# ALLOW redundant_import Prelude.(<$>) #-}
...
> 3. Attach a `{-# ALLOW redundancy_import #-}` pragma to an import,
> import {-# ALLOW redundant_import #-} Control.Applicative
...
> 4. Attach a `{-# ALLOW redundancy_import #-}` pragma to a name in an
> import list,
> import Control.Applicative ((<$>) {-# ALLOW redundant_import #-})
What I don't like about this solution is how specific it is -- the gut
instinct that it can't be the last such extension, if we were to start
replacing CPP piecemeal.
And after a while, we'd accomodate a number of such extensions..
and they would keep coming.. until it converges to a trainwreck.
I think that what instead needs to be done, is this:
1. a concerted effort to summarize *all* uses of CPP in Haskell code
2. a bit of forward thinking, to include desirables that would be easy
to get with a more generic solution
Personally, I think that any such effort, approached with generality
that would be truly satisfying, should inevitably converge to an
AST-level mechanism.
..but then I remember how CPP can be used to paper over incompatible
syntax changes..
Hmm..
--
с уважениeм / respectfully,
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