I am trying to typeset the grammars needed to describe the applied pi calculus. The outcome should look somewhat similar to the following attached example, especially concerning the alignment of the right hand side text.
To me, this does not seem to be solvable straightforward with the syntax package. Though i am fairly convinced this is the package to go with, i have no idea on how to typeset such a layout despite reading the documentation. The grammar-environement seems to be rather restrictive. Any ideas are thus highly appreciated.