Hi, again! Here are the missing links to my previous e-mail: [1] https://github.com/ghc-proposals/ghc-proposals/pull/111#issuecomment-4372719... [2] https://github.com/ghc-proposals/ghc-proposals/pull/111#issuecomment-4761252... All the best, Wolfgang Am Sonntag, den 05.05.2019, 14:02 +0300 schrieb Wolfgang Jeltsch:
Am Freitag, den 03.05.2019, 11:52 +0200 schrieb Spiwack, Arnaud:
* The file `Multiplicity`, which defines `type Mult = Type`, the `Scaled` type and functions unrestricted, linear, pattern synonyms `One` and `Omega`, quick submultiplicity test submult
Could `Omega` **please** be changed to `Many`? I argued long time ago [1] already why `Omega` seems to be a bad choice and `Many` to be a much better alternative. Unfortunately, my arguments, while having been positively received, didn’t really have a considerable impact on the proposal and implementation; still today the proposal reflects only part of them, as it did 1½ months ago [2].
Notation is important, since good notation aids and bad notation confuses. Notation is something that is very likely to stay once it has been in use. Given that changing this one identifier shouldn’t be a big deal, I’m asking you keenly to make this change.
Following are my arguments again:
1. It’s already questionable that the paper uses the symbol ω. The choice of this symbol stems from its use for the smallest transfinite ordinal number, the number that denotes the length of an infinite list, if you so wish. This doesn’t match the use of ω in this proposal, where it stands for the possibility to use a value *any number* of times and thus rather corresponds to something like ℕ ∪ {ω}.
2. Even if ω is considered okay for being used in the theory, we shouldn’t use the identifier `Omega` in Haskell. `Omega` doesn’t name the multiplicity; instead it names the symbol that is used to denote the multiplicity.
3. To people not into something like ordinal numbers or ω-words, `Omega` doesn’t mean anything. Therefore its use would rather confuse than enlighten those people.
I propose to pick multiplicity identifiers that capture the actual meanings of the multiplicities and are consistent with existing identifiers at the same time. `Control.Applicative` already uses the identifiers `some`, `many`, and `optional`. Thus we should use `Many` for what is now called `Omega` and `Optional` for the affinity multiplicity in case it’s added at some time. I think `One` is a good name and thus should be kept. The 0-multiplicity would probably be best named `None`.
All the best, Wolfgang