[Jprogramming] Why won;t this work?

[Linda Alvord]

   d=:6 _5 7 3
   r=: 13 :'(<./y),>./y'
   r
<./ , >./
   r d
_5 7
  (-i.10)
0 _1 _2 _3 _4 _5 _6 _7 _8 _9
  1{.r d 
_5
  (-i.10)<_5
0 0 0 0 0 0 1 1 1 1

   (-i.10)<1{.r d
|length error
|   (-i.10)    <1{.r d

   (-i.10)<(1{.r d)
|length error
|   (-i.10)    <(1{.r d)

   I want something like this, but this is a simple example of what doesn't
work. 

Linda