@dispatch(Projection)
def rowfunc(t):
 from toolz.itertoolz import getter
 indices = [t._child.fields.index(col) for col in t.fields]
 return getter(indices)

@ dispatch ( Projection ) def rowfunc ( t ) : from toolz . itertoolz import getter indices = [ t . _child . fields . index ( col ) for col in t . fields ] return getter ( indices )
rowfunc provides a function that can be mapped onto a sequence .