Is USE_REPORT_PRELUDE still useful?

Edward Kmett ekmett at
Wed Oct 29 14:31:41 UTC 2014

Ack! That -is- a somewhat scary invisible backdoor dependency. :/

We ripped out a lot of unused and untestable ifdefs for other compilers from base a couple of years back, I'd be curious if this was already affected.

Any idea where the code for the report generation lies?


On Oct 29, 2014, at 5:18 AM, Malcolm Wallace <malcolm.wallace at> wrote:

> On 29 Oct 2014, at 00:24, David Feuer wrote:
>> A lot of code in GHC.List and perhaps elsewhere compiles differently depending on whether USE_REPORT_PRELUDE is defined. Not all code differing from the Prelude implementation. Furthermore, I don't know to what extent, if any, such code actually works these days. Some of it certainly was not usable for *years* because GHC.List did not import GHC.Num.
> I'm not completely certain, but I have a vague feeling that the Haskell Report appendices that define the standard libraries might be auto-generated (LaTeX/HTML/etc) from the base library sources, and might use these #ifdefs to get the right version of the code.
> Regards,
>    Malcolm
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