Monadic & (where)

Returns integer vector of true positions in boolean vectors.

Syntax: &x; where x; &[x]; where [x]

o)&0101b
1 3
o)&(1>-1 0 1)
0 1
o)

When applied to integer vector, generates N indices of corresponding elements.

o)&1 2 3
0 1 1 2 2 2
o)where 2 3 0 1
0 0 1 1 1 3
o)