flat_map

[Yoriyasu Yano]

Hey,

I noticed that flat_map on a bloom collection will cause it to cycle through the collection twice (demonstrated in pasted code below).

Is this intentional?

CODE:

class B

  include Bud

  state do

    scratch :t, [:a, :d]

    scratch :b, [:a, :dp]

  end

  bloom :test do

    b <= t.flat_map do |p|

      puts p.inspect

      p.d.map {|g| [p.a, g]}

    end

  end

end

b = B.new

b.t <+ [[1, [["a", "a"], ["b", "b"]]]]

b.tick

OUTPUT:

[1, [["a", "a"], ["b", "b"]]]

[1, [["a", "a"], ["b", "b"]]]

--

Yoriyasu Yano

University of California, Berkeley

BA Cognitive Science and Computer Science

[Joseph Hellerstein]

In general, rule bodies may be eval'ed many times per tick, so side-effects in rule bodies are not a good idea!

Note that BudCollections have set semantics, so eval'ing the rhs multiple times per tick shouldn't affect the lhs (unless you do side-effecting stuff in bodies!)

In future versions of Bud, side-effects in the body will be forbidden...

J