Literate programming in Ruby

lit.rb

def lit(src)
  eval src.split("\n").delete_if { |l| l[0]!='>' }.map {|l| l[1,l.length] }.join("\n")
end

lit <<src
This is a big wall of text with no Ruby code...
Does this work?
1 1 + .

I bet it didn't... maybe the following works:
> puts 8675309
Yay!

You can create functions that span multiple lines
> def foo
We interrupt this program to bring you the following:
> 12 ; end;

Now, we can run foo:
> puts foo

src