It's funny, because the with/let forms in Arc immediately struck me as quite sensible. Both include an implicit 'do', (or 'progn', for the crusty oldsters like me) and so need a bounded number of forms to scan for new bindings. In the case of a 'with' form, there could be any number of terms, to the parens around the list of forms are needed. The 'let' form, on the other hand, only binds a single identifier, so the first and second parameters to the form are always going to be the term name and value, respectively.
