Correct parsers for bounded integral values

[Stefan Klinger]

Hello,

I'd like to bring to your attention a discussion that I have started
over at Haskell-cafe [1].  I was complaining about the silent overflow
of parsers for bounded integers:

    > read "298" :: Word8
    42

I find this unsatisfying, and I have demonstrated a solution [2] that
seems correct and performant.

To avoid cross posting, I'd rather point you to the discussion on the
Haskell-cafe mailing list [1].

I would like to help get this into GHC and also other parsing
libraries.  Not all libraries suffer from this issue, but some do,
including GHC and its `base` package.

How can I attempt this?  Should I file a bug report?  Or try to follow
the instructions at ghc.dev [3] and submit a pull request?  I would
start tinkering at [this point][4] as soon as I manage to compile GHC.

Would you want to share any advice beforehand?  I'd really appreciate
to be stopped before wasting effort ;-)  Also, I probably only can work
on this on weekends.

Cheers
Stefan


[1]: https://mail.haskell.org/pipermail/haskell-cafe/2025-July/137134.html
[2]: https://github.com/s5k6/robust-int
[3]: https://ghc.dev/
[4]: https://hackage.haskell.org/package/ghc-internal-9.1201.0/docs/src/GHC.Internal.Read.html#line-586


--
Stefan Klinger, Ph.D. -- computer scientist              o/X
http://stefan-klinger.de                                 /\/
https://github.com/s5k6                                    \
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