RVM produces list trees without layout in the regular productions

[jurgenvinju]

I think I work around this now by introducing a bug in the subtype implementation at run-time, but it is not type correct behavior and will lead to subtle bugs elsewhere in the future.

After pattern matching a list out of something, like ... <{A ","}* l> ... the l will be bound to appl(regular(\iter-seps(sort("A"),[lit(",")])), ... instead of the correct appl(regular(\iter-seps(sort("A"),[layouts(...),lit(","),layouts(...)])), .... This is due to the auto-wrapping code which the compiler has to generate into the pattern matcher which should know the right regular prod to apply. It seems the layout separators are either not introduced yet there or they have been removed again (it depends on the inner workings of the type checker). Please help.

[jurgenvinju]

perhaps we should add a constructor declaration for regular as well, because the normal productions seem to be having the right layout.