[Feature] Add lambda function expressions

[lorenzholzbauer]

Is there an existing proposal for this?

• [X] I have searched the existing issues

This feature does not exist in the latest version

• [X] I am using the latest version

Proposal

Add lambda function support, which allows users to specify anonymous functions without a name that always return a value.

For example:

(x: num) => x + 1;

// Once generics are implemented with #
var y: Func<num, num> = (x: num) => x + 1;

Exact behaviour / changes you want

• [x] Add lambda notation and semantic analysis.
• [x] Add translation to JavaScript and TypeScript.
• [ ] Add tests

[Luna-Klatzer]

Generic type support will be implemented by #494 and #584.