[plt-scheme] SLaTeX help requested

I'm typesetting slides using the seminar, helvet, and slatex packages.

When I say \scheme|(list->string lst)|, the - comes out really stumpy (a 
hyphen, not a dash) and the > quite large. It looks awkward. So I try 
\scheme|(list-->string lst)|, and now both -'s come out as dashes. How 
do I get just one dash?

This convention also wreaks havoc in comments typeset with SLaTeX; I 
have to say

;; string-$>$list-of-charlists: string $\rightarrow$ (listof (listof char))

in order to get the line to come out looking reasonable on the slide. 
But at least I know what to do there.

Thanks. --PR