Parametric types: complex use of multiple parameters

[Steven_Sagaert]

This related discussion (although the question is about a more general case) might be useful:

Are there any (long term) plans to add higher order generics (a.k.a. higher kinded types) to Julia?

Higher order generics are useful to write very generic libraries over container data structures. In Julia such a type would look like C1{C2{T}} with C1 & C2 container types (Arrays,Lists,…) for a second order type. There could be even more abstract n-order types. If we ignore very theoretical languages like Agda,Idris,Coq, the only languages that have this - that I know of - are Haskell & Scala. Both are very powerful languages. I think Julia could benefit from such a feature as well. I wonde…