RosettaCodeData/Task/Cumulative-standard-deviation/Zkl/cumulative-standard-deviation.zkl

fcn sdf{ fcn(x,xs){
      m:=xs.append(x.toFloat()).sum(0.0)/xs.len();
      (xs.reduce('wrap(p,x){(x-m)*(x-m) +p},0.0)/xs.len()).sqrt()
    }.fp1(L())
}