module system: types.attrsWith { nameType, valueType, ... }?

[roberth]

Project description

Some attribute sets are not allowed to contain any string as attribute name.
This type will add nameType to allow restriction of the names.
It may also add nameConfigPath (represented by the figurative ... in the title) to allow an alternative name for what's currently the _module.args.name config value path. (When reconsidering #177576)

I'd suggest this type to be lazy like lazyAttrsOf, or at least make that the default behavior (lazy ? true).

Example:

• nixosTest node names must be valid python identifiers
  nixos/test-driver: use attrname from nodes to refer to machines #181482
• some key-value formats may reject empty names or names with weird characters such as newlines