Version 2.30 added support for contexts in datatype and member function definitions, Haskell style arrays, an external function calling mechanism for gofc, an experimental implementation of Launchbury/Peyton Jones style lazy functional state threads, an experimental implementation of "do" notation for monad comprehensions.
[The implementation of the Gofer functional programming system, Mark P. Jones, Research Report YALEU/DCS/RR-1030, Yale University, Department of Computer Science, May 1994. FTP: nebula.cs.yale.edu/pub/yale-fp/reports].