Deprecate `_≺_` in `Data.Fin.Base`

[MatthewDaggitt]

I think we already have more than enough definitions of this relation (I think this is the 5th?), and I'd prefer to have less. This is a moderately odd definition with virtually no properties about it.

Anybody object to the deprecating it in v2.0? I'll ask on Zulip as well.

[jamesmckinna]

Did you ask on Zulip? I was beginning to wonder if the #stdlib channel/stream should have a specific > deprecation or > RFC (or something of that ilk...) sub-channel/stream for discussion of proposed changes, esp. wrt deprecation and/or labelled as breaking (cf. issue #1636)

[MatthewDaggitt]

Nope, not yet. Will do so now.

[MatthewDaggitt]

Asked.

[jamesmckinna]

It looks as though, from the deafening silence here, that this deprecation, at least, will (and should!) go through...

[JacquesCarette]

I've never used it, so I won't miss it! 😁

[jamesmckinna]

Whatever happened to this? Removing it eventually will yield some more dependency simplification arising from #1837...

[JacquesCarette]

Looks caught in the lack of available cycles from the maintenance team. I'll assign myself, in a great fit of hope.

[jamesmckinna]

It looks as if, perhaps, this was a relic from early/earlier experiments with Data.Fin.Induction... (?), and recent commits to that make no use of this relation.

[jamesmckinna]

So I now have a branch with this almost working: but the main thing in Data.Fin.Properties is to show this relation equivalent to _<_. Now, if such a relation (and its constructor, coding for a cute inversion principle akin to Data.Fin.Properties.toℕ< ) is to be deprecated, how do I go about deprecating properties of it? I can't seem to avoid getting the deprecation warnings arising from even mentioning the relation symbol.

[jamesmckinna]

I suppose one solution might be to only deprecate the constructor in Data.Fin.Base, and then deprecate the relation+properties in Data.Fin.Properties?

[jamesmckinna]

@JacquesCarette how have you got on progressing a solution? Discuss f2f on Wednesday?