gistfile1.rb

def reductions(f, acc, coll)
  F.lazy_seq do
    if coll = coll.seq
      nacc = f[acc, coll.first]
      F.cons(nacc, reductions(f, nacc, coll.rest))
    end
  end
end


def reductions(f, acc, coll)
  F.lazy_loop(acc, coll) do |recur, a, c|
    if c = c.seq
      nacc = f[acc, c.first]
      F.cons(nacc, recur[nacc, c.rest])
    end
  end
end