SizeCompare is a small library providing size comparison functions standard Haskell data-types. Size compare runs in O(min(n,m)) for both arguments, possibly faster. Instead of measuring both containers and comparing the result, SizeCompare iteratively deconstructs both sides of the equality equation until a conclusion can be made. A common expression like: length xs > 0 runs O(n) in the length of the list. Sizecompare runs (O(1)) in this particular case: xs |>| 0 This is still an initial version of the library and updates may follow after some more profiling.