factorial.mu


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# example program: compute the factorial of 5

def main [
  local-scope
  x:num <- factorial 5
  $print [result: ], x, [ 
]
]

def factorial n:num -> result:num [
  local-scope
  load-ingredients
  {
    # if n=0 return 1
    zero?:boolean <- equal n, 0
    break-unless zero?
    return 1
  }
  # return n * factorial(n-1)
  x:num <- subtract n, 1
  subresult:num <- factorial x
  result <- multiply subresult, n
]

# unit test
scenario factorial-test [
  run [
    1:num <- factorial 5
  ]
  memory-should-contain [
    1 <- 120
  ]
]