xashor

    (a -> b) -> T a -> T b
  T (a -> b) -> T a -> T b
  (a -> T b) -> T a -> T b

    echo@> (2{ARGV) -.&([: <;._1 LF, 1!:1) (3{ARGV)
    NB.    2nd arg                          3rd arg
    NB.              g&f execute f for each, then g on both
    NB.                              1!:1 read file
    NB.                          LF, prepend newline
    NB.                 [: <;._1 split based on first char
    NB.             -.  remove right elements from left array
    NB. echo@> echo each line
    exit 0

    $ time j9 -c ./pseudo_grep.ijs test_b test_a
    …
    real   0m0.064s
    user   0m0.032s
    sys    0m0.017s
    $ time grep -vf test_b test_a
    …
    real   0m5.815s
    user   0m5.234s
    sys    0m0.576s

  // p={(x0,y0),(x1,y1),...} and v={(vx0,vy0),(vx1,vy1),...}
  for(int j=0;j<2*SIZE;j++)p[j]+=v[j];

  // pv={(x0,y0,vx0,vy0),(x1,y1,vx1,vy1),...}
  for(int j=0;j<4*SIZE;j+=4)
    pv[i+0]+=pv[i+2],pv[i+1]+=pv[i+3];

  LABEL = sys._getframe().f_lineno
  print(1)
  j(LABEL)