NB.  Remove bs from a character list
no_bs =: monad define
if. (#y.) > t =. y. i. 8{a.
  do. no_bs ((<:t) {. y.) , (>:t)}.y.
  else. y.
end.
)

no_bs =: monad define
while. (#y.) > t =. y. i. 8{a.
  do. b =: y. =. ((<:t) {. y.) , (>:t)}.y.
end.
y.
)

readline =: monad define
'p o i' =. 2!:2'readline'
y. 1!:2 i
1!:22 i
2!:3 p
x =. ((>: z i. 10{a.) }. z=. 1!:1 o), 10{a.
1!:22 o
x
)

NB. foo=: readline &. > (< ;. 2 read'20021016')

fix =: dyad define
ap =. (1!:3) & (< x.)
0$(ap &. >) readline &. > (< ;. 2 read y.)
)