Ralf Hinze and Ross Paterson, Journal of Functional Programming 16(2):197–217, 2006. doi:10.1017/S0956796805005769 Summary We present 2-3 finger trees, a functional representation of persistent sequences supporting access to the ends in amortized constant time, and concatenation and splitting in time logarithmic in the size of the smaller piece. Representations achieving these bounds have appeared