Playing with CoffeeScript and underscore.coffee

gistfile1.txt

  # Check CoffeeScript

  square = (x) -> x * x
  puts "'2' squared: #{square 2}"

  
  # See if underscore.coffee is loaded

  puts "underscore version: #{_.VERSION}"

  
  # Some printing utility functions

  printArray = (name, xs) -> puts "'#{name}': [#{xs}]"
  printArraySize = (name, xs) -> puts "'#{name}' has #{_.size xs} elements"

  printArrayAndItsSize = (name, xs) -> 
    printArray name, xs
    printArraySize name, xs

  yesNo = (b) -> if b then "Yes" else "No"

  
  # Define some arrays

  xs = [1..100]
  printArraySize "xs", xs
  
  tens = [1..10]
  printArray "tens", tens
  
  # Return all but the last element in an array

  init = (xs) -> xs[0...(_.size xs.length) - 1]

  printArray "init tens", init tens

 
  # Naive functions for working with tuples as arrays  

  fst = (tp) -> tp[0]
  snd = (tp) -> tp[1]


  # Nice example of using _.zip, _.tail, ._map, and _.all

  isConsecutive = (xs) -> 
    xsInit = init xs
    xsRest = _.tail xs
    xsZip = _.zip xsInit, xsRest
    _.all _.map xsZip, (tp) -> (fst tp) + 1 == (snd tp)

  puts "Is tens consecutive? #{yesNo isConsecutive tens}"
  
  nonConsecutive = [1..4].concat [6..10]

  printArray "nonConsecutive", nonConsecutive
  puts "Is nonConsecutive consecutive? #{yesNo isConsecutive nonConsecutive}"


  # Returns true if argument is even

  even = (n) -> n % 2 == 0

  anEvenNumber = 10
  anOddNumber = 9

  evenNumberUI = (n) -> puts "Is #{n} an even number? #{yesNo even n}"

  evenNumberUI anEvenNumber
  evenNumberUI anOddNumber


  # Returns all even numbers from an array

  evens = (ys) -> _.filter ys, even
  printArraySize "evens xs", (evens xs)
    

---- OUTPUT ----

'2' squared: 4
underscore version: 1.1.0
'xs' has 100 elements
'tens': [1,2,3,4,5,6,7,8,9,10]
'init tens': [1,2,3,4,5,6,7,8,9]
Is tens consecutive? Yes
'nonConsecutive': [1,2,3,4,6,7,8,9,10]
Is nonConsecutive consecutive? No
Is 10 an even number? Yes
Is 9 an even number? No
'evens xs' has 50 elements


---- A naive 'build script'. I need to learn how to do this in reality... ----

cat underscore.coffee > tmp____.coffee
cat world.coffee >> tmp____.coffee
coffee tmp____.coffee
rm tmp____.coffee