I believe you could also use the heterogeneous map (HMap) type if you wanted static typing: (defalias Pid (HMap :complete? true :mandat

I believe you could also use the heterogeneous map (HMap) type if you wanted static typing: (defalias Pid (HMap :complete? true :mandatory {:set-point Num :k-p Num :k-i Num :k-d Num :error-sum Num :error-last Num :output-max Num :output Num})) And then use it as you might expect: (ann calculate-pid [Pid Num -> Pid]) There's no real downside to using a record, but they're really only necessary for polymorphism.