The manual says you can use "as" to bind row variables in a type, so
"#myclass as 'a -> 'a" would be the type of a function to and from equal
types, instead of possibly different descendants of "#myclass".

  But I've had trouble using this type expression in type definitions.

  #type 'a mytype = Mk of #myclass;;
  Unbound row variable in #myclass

is an error as expected, but

  #type 'a mytype = Mk of #myclass as 'a;;
  Unbound row variable in #myclass

yields the same problem.  Shouldn't this be possible?

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Frank Christoph                 Next Solution Co.      Tel: 0424-98-1811
christo@nextsolution.co.jp                             Fax: 0424-98-1500