set:{[v;i;d].[v;i;:;d]}
get:{[v;i]v . i}
bang:{[v;i]@[i;j;:;!:'(^v)j:&i~'_n]}
paths:(,/,/:\:)/,//'
take:{[i;d]((,/^:'i),(#i)_^d)#d}
dot2:{[v;i]:[@i;get[v]i;4:i;v get/:i;take[i]v get/:paths i:bang[v]i]}
dot3:{[v;i;f]:[@i;set[v;i;f get[v]i];4:i;set/[v;i;f'v get/:i];set/[v;i;f'v get/:i:paths bang[v]i]]}
dot4:{[v;i;f;d]:[@i;set[v;i;f[get[v]i]d];4:i;set/[v;i;f'[v get/:i]d];set/[v;i;d f'v get/:i:paths bang[v]i]]}