How can I define a style, in which two arguments take pairwise values in a list? In my case, the style is
\tikzset{
loop/.style 2 args={decoration={markings,
mark=at position {#1} with {\arrow{>},
\node[anchor=\pgfdecoratedangle-90] {$p_{#2}$};}},
postaction={decorate}}
}