Changing GHC Error Message Wrapping

[Andrew Gibiansky]

Thanks Simon.

In general I think multiline tuples should have many elements per line, but
honestly the tuple case was a very specific example. If possible, I'd like
to change the *overall* wrapping for *all* error messages - how does `sep`
know when to break lines? there's clearly a numeric value for the number of
columns somewhere, but where is it, and is it user-adjustable?

For now I am just hacking around this by special-casing some error messages
and "un-doing" the line wrapping by parsing the messages and joining lines
back together.

Thanks,
Andrew


On Mon, Jan 6, 2014 at 7:44 AM, Simon Peyton-Jones <simonpj at microsoft.com>wrote:

>  I think it’s line 705 in types/TypeRep.lhs
>
>
>
> pprTcApp p pp tc tys
>
>   | isTupleTyCon tc && tyConArity tc == length tys
>
>   = pprPromotionQuote tc <>
>
>     tupleParens (tupleTyConSort tc) (sep (punctuate comma (map (pp
> TopPrec) tys)))
>
>
>
> If you change ‘sep’ to ‘fsep’, you’ll get behaviour more akin to
> paragraph-filling (hence the “f”).   Give it a try.  You’ll get validation
> failure from the testsuite, but you can see whether you think the result is
> better or worse.  In general, should multi-line tuples be printed with many
> elements per line, or just one?
>
>
>
> Simon
>
>
>
> *From:* ghc-devs [mailto:ghc-devs-bounces at haskell.org] *On Behalf Of *Andrew
> Gibiansky
> *Sent:* 04 January 2014 17:30
> *To:* Erik de Castro Lopo
> *Cc:* ghc-devs at haskell.org
> *Subject:* Re: Changing GHC Error Message Wrapping
>
>
>
> Apologize for the broken image formatting.
>
>
>
> With the code I posted above, I get the following output:
>
>
>
> Couldn't match expected type `(GHC.Types.Int,
>
>                                GHC.Types.Int,
>
>                                GHC.Types.Int,
>
>                                t0,
>
>                                t10,
>
>                                t20,
>
>                                t30,
>
>                                t40,
>
>                                t50,
>
>                                t60,
>
>                                t70,
>
>                                t80,
>
>                                t90)'
>
>             with actual type `(t1, t2, t3)'
>
>
>
> I would like the types to be on the same line, or at least wrapped to a
> larger number of columns.
>
>
>
> Does  anyone know how to do this, or where in the GHC source this wrapping
> is done?
>
>
>
> Thanks!
>
> Andrew
>
>
>
> On Sat, Jan 4, 2014 at 2:55 AM, Erik de Castro Lopo <mle+hs at mega-nerd.com>
> wrote:
>
>  Carter Schonwald wrote:
>
> > hey andrew, your image link isn't working (i'm using gmail)
>
> I think the list software filters out image attachments.
>
> Erik
> --
> ----------------------------------------------------------------------
> Erik de Castro Lopo
> http://www.mega-nerd.com/
>
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>
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