nofuse.scala

(a1:vec[float],a0:vec[vec[float]],a2:vec[float]) =>
          map(
            zip(
              a1,
              map(
                map(
                  a0,
                  (b:vec[float]) =>
                    res(
                      for(
                        b,
                        vecBuilder[float](784),
                        (vb:vecBuilder[float],i:long,x:float) =>
                          merge(vb,(x*lookup(a2,i)))
                      )
                    )
                ),
                (a:vec[float]) =>
                  agg(
                    a,
                    0.0F,
                    (cur:float,v:float) =>
                      (cur+v),
                    (cur:float,v:float) =>
                      (cur+v)
                  )
              )
            ),
            (a:{float,float}) =>
              (a.0-a.1)
          )

The shape of input vectors are
a0 [500]
a1 [500,784]
a2 [784]