Exploration on to_proc and each

symbol_hash_to_a.rb

# Its easy really, you want the proc to 'plus' to arguments really, so 
# just put a plus in there!
# (Or: Most flagrant abuse of unary plus)
class AsArgument < Struct.new(:symbol)
  def to_proc
    proc { |el| send(symbol, el) }
  end
end

class Symbol
  def +@
    AsArgument.new(self)
  end
end

a = ["hello", "HeLlO"]
a.each(&+:p)

Big thumbs up! And a nice solution too.
I really wanted to use the splat since it is such a "Map-Reduce-Thingy". I (apparently falsely) assumed it would call try to call to_ary before calling to_a… Will need to investigate further.

yep. Based on the assumption that Ruby enforces the array return on splat, I just used something equally short and memorable. But of course, the splat would be much more related to the problem - good luck in that search ;)