What is better way how to define a function on RDD?

# as Proc
rdd.map(lambda{|x| x*2})

# as block
rdd.map {|x| x*2}

Which method should be supported?

As Proc:

• the same way as in Python
• currently implemented

As block:

• what about aggregate(zero_value, seq_op, comb_op)
• method needs 2 function

Both:

• what about reduce_by_key(f, num_partitions=nil)

• if you would like to use block and num_partitions:

    rdd.reduce_by_key(nil, 2){|x,y| x+y}