New subject: [polyml] structure/signature matching regression in SVN

7 Apr 2009


      ...
From recent SVN commit messages, I see that there has been some
reorganization of structure/signature matching; apologies if the 
reorganization is incomplete (i.e., not ready for testing) and/or the 
following is a known issue.
This program type checks under PolyML 5.2.1 (and SML/NJ 110.68 and
MLton 20070826), but reports type errors under PolyML SVN HEAD.
=====
signature UNIQUE_SET_STRUCTS =
    sig
       structure Element:
          sig
             type t
          end
    end
signature UNIQUE_SET =
    sig
       include UNIQUE_SET_STRUCTS
       type t
       val toList: t -> Element.t list
    end
structure UniqueSetRep =
    struct
       datatype 'a t = T of {elements: 'a list}
    end
functor UniqueSet (S: UNIQUE_SET_STRUCTS): UNIQUE_SET =
    struct
       open S
       type elements = Element.t list
       structure Tree: sig
                          structure Set:
                             sig
                                type t
                                val toList: t -> elements
                             end
                       end =
          struct
             structure Set =
                struct
                   open UniqueSetRep
                   type t = Element.t t
                   fun new elements = T {elements = elements}
                   fun elements (T {elements, ...}) = elements
                   val toList = elements
                end
          end
       open Tree.Set
    end
=====