Provide binder for composed views

[bastian-koepcke]

In order to not having to write a repeating composition of views every time it is used, provide a binder that enables binding composed views. This is similar to defining a function and requires a signature and body Since the body does not contain sequencing, we write = instead of a function body { .. }.

view view_name<generic_args: k...>(param_name: T, ..., input_view: [[U; n]]) -> T = input_view.v.v...

• Parameters can have a data type or a view-function type.
• The last parameter must be for the array view that is transformed. It therefore has an array view type.
• Special syntax definition for view function body?
• introduce type checking rule for composition of (view) functions .?