Specs for Functions and Callbacks
The @spec specifies a function’s parameter count, types, and return-value type. It can appear anywhere in a module that defines the function, but by convention it sits immediately before the function definition, following any function documentation.
We’ve already seen the syntax:
@spec function_name( param1_type, …) :: return_type
Let’s see some examples. These come from the built-in Dict module.
| 1: | @type key :: any |
| 2: | @type value :: any |
| 3: | @type keys :: [ key ] |
| 4: | @type t :: tuple | list # `t` is the type of the collection |
| 5: | |
| 6: | @spec values(t) :: [value] |
| 7: | @spec size(t) :: non_neg_integer |
| 8: | @spec has_key?(t, key) :: boolean |
| 9: | @spec update(t, key, value, (value -> value)) :: t |
- Line 6
-
values takes ...
Get Programming Elixir 1.2 now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
