echo.ipynb

echo.rb

# print an return, print is side effect
identity_print = lambda { |x|
  puts x
  x
}
word = lambda {
  # return a random word of minimum length 3
  (3..(7..20).to_a.sample).to_a.sample.times.map { 
      ('a'..'z').to_a.sample }.join
}

_quit = lambda { # quit is a keyword in Ruby?!
  # return the string 'quit'
  'quit'
}

# make a list of random strings and insert 'quit' randomly
random_words = lambda {
  stop = (5..20).to_a.sample
  samples = (3..stop).to_a.sample.times.map { 
    word[]
  }
  # samples.compact
  samples.insert (1..samples.length).to_a.sample, _quit[]
}

# return a random word, emulating user input
_input = lambda {
  random_words[].sample
}

# recursion
echo_FP = lambda {
  identity_print[_input[]] == _quit[] or echo_FP[]
} 
echo_FP[]

fp_echo.py

# FP version of "echo()"
def identity_print(x):      # "identity with side-effect"
    print(x)
    return x
echo_FP = lambda: identity_print(input("FP -- "))=='quit' or echo_FP()
echo_FP()

fp_echo_words.ipynb