[Haskell-cafe] Dealing with GHC 7.10 prelude imports

[Nikita Volkov]

You can use a custom Prelude. E.g., the "base-prelude" project takes care
of this problem: http://hackage.haskell.org/package/base-prelude


2015-04-12 11:14 GMT+03:00 Alan & Kim Zimmerman <alan.zimm at gmail.com>:

> See https://ghc.haskell.org/trac/ghc/wiki/Migration/7.10.
>
> I have just solved one of these by doing
>
> {-# LANGUAGE CPP #-}
> #if __GLASGOW_HASKELL__ < 709
> import Data.Monoid hiding ((<>))
> #endif
>
> Alan
>
>
> On Sun, Apr 12, 2015 at 9:55 AM, Brendan Hay <brendan.g.hay at gmail.com>
> wrote:
>
>> Hi,
>>
>> I've run into a couple of cases when attempting to support multiple GHC
>> versions in my libraries (7.6.3 -> 7.10) where I've repeatedly made
>> mistakes
>> due to being warned about unused imports for various modules that are now
>> part
>> of the Prelude such as Data.Monoid, Data.Foldable, etc. which I
>> subsequently
>> remove either manually or via editor automation sufficiently
>> indistinguishable
>> from magic.
>>
>> This then results in successful compilation on 7.10 and failure on earlier
>> versions of GHC due to missing imports (ie. Data.Monoid (mappend,
>> mempty)),
>> which prior to my current workflow of manually building on multiple
>> versions of
>> GHC before releasing a new version, manifested once or twice only after
>> uploading to Hackage.
>>
>> Now this is all user/workflow error on my part, but I wondered if others
>> have
>> some kind of trick up their sleeve for avoiding these kind of issues? I
>> could
>> attempt to tailor the compiler's warning flags appropriately, but it
>> bodes ill for
>> spotting genuinely unused imports.
>>
>> Cheers,
>> Brendan
>>
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>
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