Feature request: multi-part exercises #331
Description
It would be extremely useful to be able to organize an exercise into sub-parts, perhaps similarly in layout to the tutorials where you can navigate through the sections using left and right arrows at the top of the screen.
Each sub-part would have its own prelude, prepare, template/editor, description, and solution. They could all share a toplevel (though there might be some issues to work out here wrt prelude/prepare definitions).
This would be very helpful because often later parts of an exercise will rely on successfully implementing the earlier functions. For example, part a) of an exercise will require the student to implement a function f, and then parts b) and c) involve making use of f. If a student is unable to implement f, they will be harshly penalized by the autograder on parts b) and c) of the exercise as well. In contrast, when manually grading an assignment we could still grade the student on parts b) and c) independently, if they are still able to use f properly assuming a correct implementation.
This is especially a problem with exercises involving modules. In a recent exercise, we wanted students to implement a module M with an abstract type t, and later wanted them to implement a functor F (M): S with type t = M.t (where S was some signature) and apply it to M resulting in a module M2. We were unable to test the module M2 since its type involved some types defined by the student in their solution, so we were not able to provide this type in our grader code.
Splitting the assignment up into several exercises, each with the previous questions implemented in the prepare.ml file, would have been a way to get around this, but we felt that doing this was a bit clunky and confusing. Being able to split up an exercise into sub-exercises which can be navigated between on a single page seems like a good solution to this.