Implement tuples about lambda HOT 3 OPEN

This is actually mandatory because lists are not well suited to specify the arguments for native functions because they have uniform inner type. When the type system is activated, it will no longer be possible to specify heterogeneous arguments to native functions. Therefore, tuples must be used.

Marking this as a bug.

from lambda.

Tuple types must always be included in round brackets, otherwise the commas would create an ambiguous syntax:

fn x: string, string -> ...

The above is actually not ambiguous in current versions of Lambda because string is a keyword and can't be used as a parameter name, but the parser for that wouldn't be easy to implement. It is way better to disambiguate like this:

fn x: (string, string) -> ...

from lambda.

TODO list:

• deconstructions,
• operators,
• string formatting.

Operators can only be applied on tuples of the same arity. Applying an operator to a pair of tuples is equivalent to applying it to each pair of elements.

from lambda.