`map` expansion and starring

[HighDiceRoller]

• Allow switching star after first repeat?

Decided against this.

• Should star=True expand dice within the first argument?

Against:

• Added complexity in implementation and API.
• Most starting states are singular.

For:

• This makes star behave the same as sending the unpacked arguments directly.
• Since I'm not going with star switching after first repeat, this effect would require explicit tupleize otherwise.

Decision: I'm going to hold off at least for now.

• Explicit NoExpand wrapper to prevent expansion?

Done.

[HighDiceRoller]

star switching as a problem: not only do we need to infer star, we need to replace a number of original arguments equal to the output arity of repl. For example:

map(lambda x, y: (x, y), 0, 1, repeat=10)

should keep producing (0, 1), but this requires removing both 0 and 1. This seems sufficiently unintuitive that I'd rather force the initial state to be explicitly tupled.

[HighDiceRoller]

Backed off on this for now, pending deciding if/how to forward **kwargs in #218 .

[HighDiceRoller]

Decided to make keyword-only arguments non-expanding. Not sure whether I want to do this for simpler functions as well, e.g. die.reroll().