Changelog for Elixir v1.20

Type system improvements

Full type inference

Elixir now performs inference of whole functions. The best way to show the new capabilities are with examples. Take the following code:

def add_foo_and_bar(data) do
  data.foo + data.bar
end

Elixir now infers that the function expects a map as first argument, and the map must have the keys .foo and .bar whose values are either integer() or float(). The return type will be either integer() or float().

Here is another example:

def sum_to_string(a, b) do
  Integer.to_string(a + b)
end

Even though the + operator works with both integers and floats, Elixir infers that a and b must be both integers, as the result of + is given to a function that expects an integer. The inferred type information is then used during type checking to find possible typing errors.

Acknowledgements

The type system was made possible thanks to a partnership between CNRS and Remote. The development work is currently sponsored by Fresha and Dashbit.

v1.20.0-dev

1. Enhancements

Elixir

• [Enum] Add Enum.min_max sorter
• [Integer] Add Integer.ceil_div/2
• [Kernel] Print intermediate results of dbg for pipes
• [Kernel] Warn on unused requires
• [Regex] Add Regex.import/1 to import regexes defined with /E

ExUnit

• [ExUnit.CaptureLog] Add :formatter option for custom log formatting

Mix

• [mix test] Add mix test --dry-run

2. Bug fixes

3. Soft deprecations (no warnings emitted)

4. Hard deprecations

Elixir

• [File] File.stream!(path, modes, lines_or_bytes) is deprecated in favor of File.stream!(path, lines_or_bytes, modes)
• [Kernel] Matching on the size inside a bit pattern now requires the pin operator for consistency, such as <<x::size(^existing_var)>>
• [Kernel.ParallelCompiler] Kernel.ParallelCompiler.async/1 is deprecated in favor of Kernel.ParallelCompiler.pmap/2, which is more performant and addresses known limitations

Logger

• [Logger] Logger.*_backend functions are deprecated in favor of handlers. If you really want to keep on using backends, see the :logger_backends package
• [Logger] Logger.enable/1 and Logger.disable/1 have been deprecated in favor of Logger.put_process_level/2 and Logger.delete_process_level/1

v1.19

The CHANGELOG for v1.19 releases can be found in the v1.19 branch.