ziv@2277: functor PairKeyFn (structure I : ORD_KEY
ziv@2277:                      structure J : ORD_KEY)
ziv@2277:         : ORD_KEY where type ord_key = I.ord_key * J.ord_key = struct
ziv@2277: 
ziv@2277: type ord_key = I.ord_key * J.ord_key
ziv@2277: 
ziv@2277: fun compare ((i1, j1), (i2, j2)) =
ziv@2277:     case I.compare (i1, i2) of
ziv@2277:         EQUAL => J.compare (j1, j2)
ziv@2277:       | ord => ord
ziv@2277: 
ziv@2277: end