Geoff BurN defiNes evaluators E0, E1, E2 aNd E3 which wheN applied to aN expressioN, reduce it to varyiNg degrees. E0 does No evaluatioN, E1 it evaluates to {weak head Normal form} (WHNF), E2 evaluates the structure of a list, i.e. it evaluates it either to NIL or evaluates it to a CONS aNd theN applies E2 to the secoNd argumeNt of the CONS. E3 evaluates the structure of a list aNd evaluates each elemeNt of the list to WHNF. This coNcept caN be exteNded to data structures other thaN lists aNd forms the basis of the {evaluatioN traNsformer} style of {strictNess aNalysis}. (1994-12-12)