ValueScript/concept-code/moduleVariables.vsm

// test_output! [1, 2, 3, 12586269025]

export @main {}

@main = function() {
  call @counter [] %_tmp0
  call @counter [] %_tmp1
  call @counter [] %_tmp2
  call @fib [50] %_tmp3

  mov [%_tmp0, %_tmp1, %_tmp2, %_tmp3]
}

// module variables are not directly accessible because they allow violation of the language's
// guarantees:
@counter = function() {
  op!== module.counter undefined %return
  jmpif %return :counter_initialized
  module_mov 0 module.counter
counter_initialized:
  op+ module.counter 1 %return
  module_mov %return module.counter
}

/*

// but allowing them in the runtime could allow the compiler to implement things like @memoize

@memoize
function fib(n: number) {
  if (n < 2) {
    return n;
  }

  return fib(n - 1) + fib(n - 2);
}

*/
@fib = function(%n) {
  op=== module.fib_results undefined %_tmp0
  jmp_if_not %_tmp0 :fib_results_initialized
  init_hash_map module.fib_results
fib_results_initialized:
  hash %n %input_hash
  hash_map_lookup module.fib_results %input_hash %found %return
  jmp_if_not %found :calculate
  end
calculate:
  op< %n 2 %n_lt_2
  jmp_if_not %n_lt_2 :recurse
  mov %n %return
  jmp :update_memory
recurse:
  op-- %n
  call @fib [%n] %return
  op-- %n
  call @fib [%n] %previous
  op+ %return %previous %return
update_memory:
  hash_submov %input_hash %return module.fib_results
}