@TechReport{Tullsen-Hudak:RR1998,
  author =       "Mark Tullsen and Paul Hudak",
  title =        "An Intermediate Meta-Language for Program Transformation",
  institution =  "Yale University",
  month =        jun,
  year =         "1998",
  number =       "YALEU/DCS/RR-1154",
  abstract =     "As part of an effort to bridge the gap between the
		  theory and practice of program transformation, we
		  have designed a meta-language for transforming
		  functional programs.  The meta-language is sound in
		  preserving both value and termination properties of
		  programs (and is thus superior to the unfold/fold
		  methodology).  Our key contribution is an equational
		  specification of Scherlis's expression procedures, in
		  which we express the essence of expression procedures
		  as a single transformation rule.  Our approach has
		  the following advantages over both unfold/fold and
		  expression procedures: (1) all program derivations
		  are reversible; (2) many transformations can be done
		  which unfold/fold and expression procedures cannot
		  do; and (3) the proof of correctness is far simpler.",
}