this paper. The syntactic restriction is now rather standard, see for example [PJPS96, Lau93, Ses97, MS99]. As usual the order of bindings in let expressions is syntacticaly irrelevant. We will require that the alternatives in case-expression are distinct and thus the order of alternatives in case-expressions is also syntacticaly irrelevant. We will sometimes us d to range over a sequence b1 ; : : : ; bn of bindings and alts to range over a sequence alt1 ; : : : ; altn of alternatives.