I haven't found askama yet, or rather, discovered it through HN here, I don't check the arewewebyet.org site too often and it's my main source of frameworks to find.

My main worry on things is that I'd rather like being able to express the inheritance in the type system through generics. Ie, having a top level "Page<T>" struct in which I can start putting the various subparts needed to render a page. It seems askama is doing it the other way round with a "parent" member needed in the child page.