Dyadic ? (search)

Searches for the first occurance of its right argument in the left one. Rеturns position index as a number or null if not found.

Syntax: <x> ? <y>; ?[<x>; <y>]

o)1 2 3 4 5 6?3
2
o)1 2 3 4 5 6?9
0N
o)

If x is a vector, ? searches for y in the left argument.

o)1 2 3?2 3 4
1 2 0N
o)
o)1 2 3?(1;2;3 4)
0
1
2 0N
o)

If x is a list of lists and y is a simple list, ? searches for y in items of x:

o)(1 2 3;(4 5 6))?4 5 6
1
o)