trying

trying

A poor man's pipes

% echo "gem 'trying'" | Gemfile
% gem install trying

Usage

String.include(Trying)
Range.include(Trying)

stream = (0..10).trying do
  to_a
  lazy
  map { |x| x ** 2 }
  first(10) # => [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
end

truth = "Foobar".trying do # => 42
  chars         # "Foobar" -> ["F", "o", "o", "b", "a", "r"]
  map(&:upcase) # %w(F o o b a r) -> %w(F O O B A R)
  map(&:ord)    # %w(F O O B A R)  -> [70, 79, 79, 66, 65, 82]
  reduce(0, :+) # [70, 79, 79, 66, 65, 82] -> 441

  # with changes the value by block
  with { |n| n * Math::PI } # 441 -> 1385.4423602330987

  # tap leaves the callee untouched
  tap { |n| puts n } # 1385.44... -> (Side effect), still 1385.44...

  # with also swallows errors
  with { |n| fail if n > 1380 } # 1385.44... -> RuntimeError

  # failed? checks for any swallowed errors
  failed? { :recover } # => RuntimeError -> :recover

  # failed? accepts specific error classes
  failed?(StandardError) { :nope }  # :recover -> :recover

  eql?(:recover) # :recover -> true
  nil?           # true -> false
  to_s           # false -> "false"
  length         # "false" -> 5

  with { |n| (n..n + 20) } # 5 -> 5..25
  to_a                     # 5..25 -> [5, 6, ..., 25]
  lazy                     # [5,  ..., 25] -> #<Enumerator::Lazy: ...>
  collect { |x| x ** 2 }   # #<Enumerator::Lazy: ...> -> #<Enumerator::Lazy: ...>
  first(5)                 # #<Enumerator::Lazy: ...> -> [25, 36, 49, 64, 81]

  reduce(1, &:*) # => [25, 36, 49, 64, 81] -> 228614400
  public_send(:/, 5443200) # 228614400 => 42
end