https://github.com/akkartik/mu/blob/main/linux/factorial.mu

     1 # compute the factorial of 5, and return the result in the exit code
     2 #
     3 # To run:
     4 #   $ ./translate factorial.mu
     5 #   $ ./a.elf
     6 #   $ echo $?
     7 #   120
     8 #
     9 # You can also run the automated test suite:
    10 #   $ ./a.elf test
    11 # Expected output:
    12 #   ........
    13 # Every '.' indicates a passing test. Failing tests get a 'F'.
    14 # There's only one test in this file, but you'll also see tests running from
    15 # Mu's standard library.
    16 #
    17 # Compare apps/factorial4.subx
    18
    19 fn factorial n: int -> _/eax: int {
    20   compare n, 1
    21   # if (n <= 1) return 1
    22   {
    23     break-if->
    24     return 1
    25   }
    26   # n > 1; return n * factorial(n-1)
    27   var tmp/ecx: int <- copy n
    28   tmp <- decrement
    29   var result/eax: int <- factorial tmp
    30   result <- multiply n
    31   return result
    32 }
    33
    34 fn test-factorial {
    35   var result/eax: int <- factorial 5
    36   check-ints-equal result, 0x78, "F - test-factorial"
    37 }
    38
    39 fn main args-on-stack: (addr array addr array byte) -> _/ebx: int {
    40   var args/eax: (addr array addr array byte) <- copy args-on-stack
    41   # len = length(args)
    42   var len/ecx: int <- length args
    43   # if (len <= 1) return factorial(5)
    44   compare len, 1
    45   {
    46     break-if->
    47     var exit-status/eax: int <- factorial 5
    48     return exit-status
    49   }
    50   # if (args[1] == "test") run-tests()
    51   var tmp2/ecx: (addr addr array byte) <- index args, 1
    52   var tmp3/eax: boolean <- string-equal? *tmp2, "test"
    53   compare tmp3, 0
    54   {
    55     break-if-=
    56     run-tests
    57     # TODO: get at Num-test-failures somehow
    58   }
    59   return 0
    60 }