[swift-evolution] [Discussion] Parentheses

Jens Persson jens at bitcycle.com
Tue Jul 5 19:57:20 CDT 2016

Please feel free to ignore this naive attempt to engage in this discussion.

My understanding of the history of Swift's tuples, argument lists, pattern
matching, associated values, etc. in two steps:

1. Initial Idealism *:
Simple powerful heavily reused general concept.

2. Iterative pragmatism / reality *:
Complicated (exceptions to) rules.

(* Inevitably not taking everything in to account.)

Has there been any recent attempts to outline a more or less complete
redesign for these things, returning to step 1 so to speak, but taking into
account what has now been learned?

As a side note (and supposedly trivial to most but me):

Parentheses (parenthesized expressions in the grammar?) are used for all of
these parts of the language, and they probably should be, but perhaps the
similarities and differences between the language constructs can be made
clearer to see by pretending that argument and parameter lists are written
with eg ≪≫ and tuples with eg ⊂⊃, etc.?

For example, I think most people agree that we should be able to use
"sloppy/forgiving" parenthetical grouping in code such as:
((1 + (2 * 3)) * (x + (-5))) - y
This is fine and can be used to express meaning for the person
reading/writing, even though it means that some of the parens can become
superfluous to a machine interpretation.

AFAICS this need not have anything to do with tuples and/or parameter
lists, but the fact that Swift is treating eg:
func foo(x: ((((Int))))) { print(x) }
func foo(x: Int) { print(x) }
((Int, Int))
(Int, Int)
seems to suggest that it somehow does.

Or maybe I have just forgotten the reasons for why there can be no such
thing as (a nested) single element tuple (type).

I also can't remember what the pros & cons of disallowing labeled single
element tuples were.

Happy to be corrected and pointed to relevant reading : )

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