Zulip Chat Archive

Stream: lean4

Topic: HasEquiv in Type?


view this post on Zulip Jason Gross (Mar 11 2021 at 21:01):

Is there a reason that HasEquiv in the standard library uses Prop rather than Sort _? I'd like to be able to use with relations that live in Type...

view this post on Zulip Mario Carneiro (Mar 12 2021 at 02:27):

Do we have universe out-params? That seems like a prerequisite for this to work

view this post on Zulip Jason Gross (Mar 12 2021 at 14:23):

I think it already works. That is to say, I've had no trouble with

class HasArr (α : Sort u1) where
  Arr : α  α  Sort u2

infix:70 " ~> " => HasArr.Arr

view this post on Zulip Leonardo de Moura (Mar 13 2021 at 15:06):

Pushed this change: https://github.com/leanprover/lean4/commit/c54a7c8ccc75e0a664560b53d26987b0a7bb861b

@Mario Carneiro We have modified the typeclass resolution procedure a few weeks ago. All universes are out-param by default now like in Lean 3.

view this post on Zulip Jason Gross (Mar 15 2021 at 17:48):

Thanks!


Last updated: May 07 2021 at 12:15 UTC