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<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">That sounds reasonable to me. I’d use –prelude-is as the flag, by analogy with –main-is; see
<a href="http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html#options-linker">
http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html#options-linker</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Haskell-Cafe [mailto:haskell-cafe-bounces@haskell.org]
<b>On Behalf Of </b>Andrew Gibiansky<br>
<b>Sent:</b> 15 July 2014 04:23<br>
<b>To:</b> Haskell Cafe<br>
<b>Subject:</b> [Haskell-cafe] Feature Proposal: GHC Flag for implicit external Prelude<o:p></o:p></span></p>
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Hey all,<o:p></o:p></p>
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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. <o:p></o:p></p>
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This would have an effect similar to -XNoImplicitPrelude and an additional<o:p></o:p></p>
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<span style="font-family:"Courier New"">import MyNewPrelude</span><o:p></o:p></p>
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in the source file. It might be a <i>little</i> different semantically, as a qualified import would disable the original implicit import, just like it does with the default Haskell prelude. <o:p></o:p></p>
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The benefit this would have is that this would give alternate preludes a more first-class status. Instead of having to import an alternative prelude everywhere, you could just have a ghc-options: --with-prelude=... flag in your *.cabal file, and have a different
prelude be used. This is important for my own work, as I highly prefer other preludes for my non-library development; I think this is a feature which will be very useful as Haskell develops and we try to figure out how to get rid of the warts in the current
Prelude. <o:p></o:p></p>
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In order to specify the actula module, I propose that you just pass the module name as the --with-prelude argument. You could thus invoke GHC like this:<o:p></o:p></p>
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ghc --with-prelude=MyNewPrelude Main.hs<o:p></o:p></p>
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Then, the same rules apply for figuring out which MyNewPrelude module you are referring to as if you had written a `import MyNewPrelude` statement in the file.<o:p></o:p></p>
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I am willing to implement this for GHC if people agree that this is a useful flag (or at least agree that isn't not a
<i>bad</i> idea).<o:p></o:p></p>
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What are your thoughts on this proposal?<o:p></o:p></p>
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<o:p> </o:p></p>
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-- Andrew<o:p></o:p></p>
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