// outline sort (factoring exercise)

o:("1.0";"1.0.1";"1.1.1";"1.2";"1.10";"1.11";"1.20";"1.20.1";"1.30";"1.9")

f:{x y z x}					/ multi-field sort
s:{1_'(&x=".")_ x:".",x}			/ split string on .
p:{,/x#,".0"}					/ pad string with .0
n:|0$+:						/ reverse cast flip
k:{f/[_n;x;n y{s y,p x-z}[|/c]'c:+/'y="."]}	/ grade y with x
u:k[<:];d:k[>:]					/ up/down

\

  u o
0 1 2 3 9 4 5 6 7 8
  o u o
("1.0"
 "1.0.1"
 "1.1.1"
 "1.2"
 "1.9"
 "1.10"
 "1.11"
 "1.20"
 "1.20.1"
 "1.30")

  \t u 1000000#0
4093