"<<"(a,b):=block([n:min(length(a),length(b))],
catch(for i thru n do (if a[i]#b[i] then throw(is(a[i]<b[i]))),
throw(is(length(a)<length(b)))))$
infix("<<")$

[1,2,3] << [1,2,4];
true

[1,2,3] << [1,2];
false

[1,2] << [1,2];
false