- ideque= elt= ideque ...procedure
Determines ideque equality, given an element-equality procedure. Ideque A equals ideque B if they are of the same length, and their corresponding elements are equal, as determined by elt=. If the element-comparison procedure's first argument is from idequei, then its second argument is from idequei+1, i.e. it is always called as (elt= a b) for a an element of ideque A, and b an element of ideque B.
In the n-ary case, every idequei is compared to idequei+1 (as opposed, for example, to comparing ideque1 to every idequei, for i > 1). If there are zero or one ideque arguments, ideque= simply returns true. The name does not end in a question mark for compatibility with the SRFI-1 procedure list=.
Note that the dynamic order in which the elt= procedure is applied to pairs of elements is not specified. For example, if ideque= is applied to three ideques, A, B, and C, it may first completely compare A to B, then compare B to C, or it may compare the first elements of A and B, then the first elements of B and C, then the second elements of A and B, and so forth.
The equality procedure must be consistent with eq?. Note that this implies that two ideques which are eq? are always ideque=, as well; implementations may exploit this fact to "short-cut" the element-by-element comparisons.