Learn A New Language

June 25, 2010

There are hundreds, probably thousands, of programming language. Some are general-purpose, others are intended for a limited domain. Some are useful, most get in your way. Some are just weird. We programmers frequently have to learn a new language, or re-learn an old one, or adapt to improvements from the vendor.

A good way to learn a new language is to write in the new language a familiar program from an old language with which you are experienced. Many people have written that they use the exercises at Programming Praxis as a way to get started with a new language.

Your task is to write a program that solves the Programming Praxis exercise of your choice in a programming language in which you are not proficient. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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4 Responses to “Learn A New Language”

  1. [...] Praxis – Learn A New Language By Remco Niemeijer The goal in today’s Programming Praxis exercise is to solve a previous exercise in a language you’re not [...]

  2. Remco Niemeijer said

    Steve Yegge’s Phone-Screen Coding Exercises using Ruby (see http://bonsaicode.wordpress.com/2010/06/25/programming-praxis-learn-a-new-language/ for a version with comments):

    def reverse(s)
        s.chars.inject {|rev, x| x + rev }
    end
    
    def fib(n)
        (2..n).inject([0,1]) {|fs, i| [fs[1], fs[0] + fs[1]]} [[1, n].min]
    end
    
    def timestable
        (1..12).map {|r| puts (1..12).map {|c| "%4d" % (r * c)}.join}
    end
    
    def sum_from_file(file)
        File.open(file) {|f| f.readlines.map(&:to_i).inject(:+)}
    end
    
    def odd_numbers
        p (1..99).find_all(&:odd?)
    end
    
    def maximum(array)
        array.inject {|max, i| i > max ? i : max}
    end
    
    def to_rgb(r, g, b)
        sprintf("%02x%02x%02x", r, g, b)
    end
    
  3. Bill B said

    I did the Texas Hold’Em problem in Ruby. For the rest of the code go to http://codingjunkie.net

    require ‘deck’
    require ‘card’
    require ‘player’

    card_deck = Deck.new
    keep_running = true

    while keep_running
    results = {}
    card_deck.shuffle
    seven_cards = card_deck.deal
    seven_cards.sort!
    copy = Array.new(seven_cards)

    puts “Press enter to deal cards..”
    line = gets

    if line.chop == “quit”
    keep_running = false
    else
    for i in 0..5
    for j in i..5
    copy.delete_at(i)
    copy.delete_at(j)
    hand = Player.check_hand(copy,0,0,nil)
    if results[hand]
    copy = Player.compare_hands(copy, results[hand], 4)
    end
    results[hand] = copy
    copy = Array.new(seven_cards)
    end
    copy = Array.new(seven_cards)
    end

    max_score = -1
    winning_hand = nil
    best_cards = nil
    results.each do |hand, cards|
    score = Player.ranks[hand]
    score = score.nil? ? cards[4].value : score
    if score > max_score
    max_score = score
    score = Player.ranks[hand]
    best_cards = cards
    winning_hand = hand
    end
    end
    puts “Best hand from #{seven_cards.join(“, “)} ”
    puts “\n\t #{winning_hand} : #{best_cards.join(“, “)}”
    end

    end

  4. Jebb said

    The golden ratio exercise from July 10 2009 in Scheme, recursively:

    (define (golden_r n)
      (if (= 0 n)
          1
          (+ 1 (/ 1 (golden (- n 1))))))
    

    and iteratively (I’ve started working my way through SICP as you can probably tell…):

    (define (golden_i n)
      (define (golden-iter n result count)
        (if (= count n)
            result
            (golden-iter n
                         (+ 1 (/ 1 result))
                         (+ count 1))))
      (golden-iter n 1 0))
    

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