Comment by chrispsn

It applies element-wise across both arrays. What you're describing is more like an each-right (+/:) or each-left (+\:).

    2019-09-25 14:44:44 2core 3gb avx2 © shakti l test
     v:3 4
     v+v
    6 8
     v+'v
    6 8
     +'[v;v]
    6 8
     v+/:v
    6 7
    7 8
    
     +/:[v;v]
    6 7
    7 8