Re: The case for transpiled generics

> On Sep 17, 2020, at 3:25 PM, Levi Morrison <levi.morrison@datadoghq.com> wrote: > >  >> >> On Thu, Sep 17, 2020 at 1:00 PM Matthew Brown <matthewmatthew@gmail.com> wrote: >>>> On Sep 17, 2020, at 1:28 PM, Brent Roose <brendt@stitcher.io> wrote: >>> But I don't want to get stuck on phrasing, if elidiing is the right term as Larry >>> suggests, let's go with it! >> >> No, the correct term is “type erasure”: >> https://en.m.wikipedia.org/wiki/Type_erasure > > "type erasure" with respect to generics means that they are checked at > compile-time and erased at run-time. For instance, Java does generics > through type erasure, and you had better believe those get checked at > compile-time! This isn't what is being proposed, at least not how I > understood it. > > Really these are just "hints", but historically in PHP the term "type > hints" meant actually type checks. > > In summary: > - Checked at run-time (and probably also compile-time when possible): > reified generics. > - Checked only at compile-time and thrown away at run-time: erased generics. > - Not checked at all: ____?. Maybe we can call them "ignored generics"? Seems like Python calls this same exact behaviour type erasure: https://www.python.org/dev/peps/pep-0484/#instantiating-generic-classes-and-type-erasure The term term type erasure is also used in documentation for an unofficial Python type checker: https://mypy.readthedocs.io/en/stable/generics.html Looks like Hack also uses the term in this context: https://docs.hhvm.com/hack/generics/type-erasure (Hack’s compiler doesn’t perform any generic type-checking)