Thank you very much Sietse! This fits my needs for the students for
tomorrow...

I also defined
\def\sprime{\myprime{\prime}}
\def\dprime{\myprime{\prime\kern-0.1em\prime}}

Then $f\sprime_x$ and $f\dprime_{xx}$ is not too hard to write :)

/Mikael


On Wed, May 22, 2013 at 2:22 PM, Sietse Brouwer <sbbrouwer@gmail.com> wrote:

> Hi Mikael,
>
> > is there a quick fix/hack that somehow allows me to get it look "almost
> like
> > it should" in a small document today with bonum?
>
> This might get you somewhere. I hope you don't have too many double
> primes in your document...
>
> NB: `%macros=mkvi` has to be the first line in the file.
>
> Cheers,
> Sietse
>
> % macros=mkvi
>
> \setupbodyfont[bonum]
>
> % This macro takes 1 arguments, #upper. It postfixes a negative kern just a
> % bit larger than the width of #upper, so that #upper does not push
> % the next content away to the right.
> \def\myprime#upper%
>    {% 1. Store the width of the primes in a box, so we can get its width
>     \setbox\scratchbox=\hbox{$#upper$}%
>     % 2. We'll want to kern back by a bit more than
>     \scratchdimen=\dimexpr \wd\scratchbox + 0.3em \relax%
>     % The actual typesetting
>     \kern 0em #upper\kern -\scratchdimen}
>
> \starttext
>     % Quick and dirty 1: just pretend the prime is uppercased
>     $f'_x$, $f_x'$ $f^{\prime\prime}_x$.
>
>     % Less quick, still dirty: the \myprime macro defined above
>     $f'_x$, $f_x'$ $f\myprime{\prime\prime}_x$.
>
>     % Slow and dirty: add a kern between the \primes,
>     % because bonum pushes them apart a bit.
>     $f'_x$, $f_x'$ $f\myprime{\prime\kern -0.1em \prime}_x$.
> \stoptext
>
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