Attached is a new patch which implements length= and the <, >, <=, >= variants in lisp. They aren't as efficient as the length= from the previous patch, especially in cases like (length= list1 list2). Since these functions can't share a bytecode with their non-length counterparts I don't know whether the trade off of a compiler macro for them is worth it. With the lisp functions the resulting bytecode would be both larger, and if none of the sequences are lists, slower as well.