list?, length, equal? and other fundamental primitives may diverge when given cyclic data. In the former two cases, avoiding this is simple and not inefficient, and the equivalents already provided in SRFI-1, in the latter case a proposal was made and rejected on the R6RS list.
Do we want to specify the behavior when these primitives encounter cyclic data?
The WG voted to accept the SRFI-1 rules, and to require that equal? MUST NOT terminate on a cyclic list.
Correction: The WG voted to make no change to R5RS.
WG1 voted:
equal? is required to do proper checks for cyclic structure to not diverge list? should return #f and length raise an error for cyclic lists
What a reason given for the rejection? Was there any rationale given for this behavior? I'd like to see what the previous editor's thought about this, and why it was chosen to be this way.