\starttext

\useMPlibrary[txt]

\startsetups text-a
    \startuseMPgraphic{followtokens}
        path RotPath ; RotPath := reverse halfcircle xyscaled 5cm ;
        draw RotPath ;
    \stopuseMPgraphic
    \followtokens{some text but not that long{\hskip1em}}
\stopsetups

\startsetups text-b
    \startuseMPgraphic{followtokens}
        path RotPath ; RotPath := reverse halfcircle xyscaled 3cm  ;
        draw RotPath ;
    \stopuseMPgraphic
    \followtokens{{\hskip1em}some text{\hskip1em}}
\stopsetups

\startMPpage
    draw textext("\setups{text-a}") ;
    draw textext("\setups{text-b}") shifted (0,-.5cm);
\stopMPpage

\stoptext

