Various solutions to Problem 1 in Project Euler (http://projecteuler.net/problem=1)

ProjEuler_prob1.rkt

; A Racket solution similar to the one-line Ruby solution.
(require racket/base)     ; Needed for in-range
(require racket/sequence) ; Needed for sequence->list

(foldl + 0 
       (filter (lambda (n) (or (= (remainder n 3) 0) 
                               (= (remainder n 5) 0))) 
               (sequence->list (in-range 0 1000))))

ProjEuler_prob1_oneline.rb

# A one-line more "functional" solution.
puts (0...1000).select { |n| n % 3 == 0 or n % 5 == 0}.inject(:+)

ProjEuler_probl1.rb

# An imperative, loop-based solution. 
result = 0
1000.times do |n|
  if n % 3 == 0 or n % 5 == 0
    result += n
  end
end

puts result