\starttext
\def\example{1--2
1---3
هٔ
}
\setupalign[r2l]
\definefontfeature[tf][arabic][tlig=yes]
\definedfont[dejavusansmono*tf]
\example

\definedfont[vazirregular*tf]
\example

\definedfont[mikhak-medium*tf]
\example

\lefttoright
\showotfcomposition{dejavusansmono*tf}{}{1--2 هٔ}
\showotfcomposition{vazirregular*tf}{}{1--2 هٔ}
\showotfcomposition{mikhak-medium*tf}{}{1--2 هٔ}

\stoptext