code / tomo-koans

   1 # Heap Allocation with `@`
   2 
   3 func main()
   4 
   5     # By default, values in Tomo are immutable.
   6     # To allow mutation, you need to allocate memory using `@`
   7 
   8     nums := @[10, 20, 30]
   9     nums[1] = 99
  10 
  11     assert nums[1] == ???
  12 
  13     nums.insert(40)
  14     assert nums[4] == ???
  15 
  16     # Allocated memory is not equal to other allocated memory:
  17     a := @[10, 20, 30]
  18     b := @[10, 20, 30]
  19     pointers_are_equal := (a == b)
  20     assert pointers_are_equal == ???
  21 
  22     # The `[]` operator can be used to access the value stored
  23     # at a memory location:
  24     contents_are_equal := (a[] == b[])
  25     assert contents_are_equal == ???
  26 
  27     # Tables also require `@` to allow modifications:
  28     scores := @{"Alice": 100, "Bob": 200}
  29 
  30     scores["Charlie"] = 300
  31 
  32     assert scores["Charlie"] == ???
  33 
  34     # Without `@`, attempting to mutate will cause an error:
  35     frozen := {"key": "value"}
  36     frozen["key"] = "new value" # <- This will break, comment it out
  37 
  38     assert frozen["key"] == "value"