print and run code blocks line by line.rb

require 'ripper'
require 'sourcify'

def lines(source)
  Enumerator.new do |out|
    source.split("\n")[1..-2].reduce("") do |buffer, line|
      buffer << "\n#{line}"
      Ripper.sexp_raw(buffer) ? (out << buffer) && "" : buffer
    end
  end
end

# @param [Binding] world  Binding to use for evaluation of statements
# @param [Proc] line2ansp Proc that takes the line to process as parameter and returns
#                         a Proc taking the result of previous line's evaluation as parameter
# @param [Proc] &block    Block of code to process.
def line_eval(world, line2ansp, &block)
  lines(block.to_source).each { |line| line2ansp[line][eval(line, world)] }
end

#example
def printrun(world = proc { binding }[], &block)
  i = 0
  line_eval(world,
            proc { |line|
              puts "#{i += 1} >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>#{line}\n --- "
              proc { |ans| puts "#{ans}\ndone!" }
            }, &block)
end

printrun do
  a = 3
  puts a
end

# careful of the current bug of sourcify with double quotes...

This version works, cheers!