: 2array  2 compress ; : bi*  '_ set dip _ execute ;  : bi@  dup bi* ;
: comb  "" split ;  : concat  "" join ;  : dip  swap '_ set execute _ ;
: first  0 extract swap drop ; : flip  comb reverse concat ;

: contains
    swap 'comb bi@ length do                    # create a matrix.
         1 - "dup 1 1 compress rotate" dip dup 0 == if break then
    loop drop length compress swap drop
    "length 1 -" bi@ rot 0 0 "'2array dip" '2array bi* swap 2array slice reverse
    : concat.(*)  concat ;
    'concat "'concat. apply" bi* eq 1 1 compress index collapse
    length if expand drop else drop 0 then ;    # r: position.
: end-with    'flip bi@ start-with ;
: start-with  'comb bi@ length rot swap iota subscript 'concat bi@ eq ;

"rosettacode" "rosetta" start-with .    # 1
"rosettacode" "taco" contains .         # 5
"rosettacode" "ocat" contains .         # 0
"rosettacode" "edoc" end-with .         # 0
"rosettacode" "code" contains .         # 7