This PR adjusts the experimental module system to not export the bodies
of `def`s unless opted out by the new attribute `@[expose]` on the `def`
or on a surrounding `section`.
---------
Co-authored-by: Markus Himmel <markus@lean-fro.org>
`[wf_preprocess]` expects a dsimp theorem, which in `Init` temporarily
have a simplistic syntactic representation until a more robust solution
is implemented.
This PR extend the preprocessing of well-founded recursive definitions
to bring assumptions like `h✝ : x ∈ xs` into scope automatically.
This fixes#5471, and follows (roughly) the design written there.
See the module docs at `src/Lean/Elab/PreDefinition/WF/AutoAttach.lean`
for details on the implementation.
This only works for higher-order functions that have a suitable setup.
See for example section “Well-founded recursion preprocessing setup” in
`src/Init/Data/List/Attach.lean`.
This does not change the `decreasing_tactic`, so in some cases there is
still the need for a manual termination proof some cases. We expect a
better termination tactic in the near future.
The linters in Batteries can be used to spot mistakes in Lean. See the
message on
[Zulip](https://leanprover.zulipchat.com/#narrow/stream/270676-lean4/topic/Go-to-def.20on.20typeclass.20fields.20and.20type-dependent.20notation/near/442613564).
These are the different linters with errors:
- unusedArguments:
There are many unused instance arguments, especially a redundant `[Monad
m]` is very common
- checkUnivs:
There was a problem with universes in a definition in
`Init.Control.StateCps`. I fixed it by adding a `variable` statement for
the implicit arguments in the file.
- defLemma:
many proofs are written as `def` instead of `theorem`, most notably
`rfl`. Because `rfl` is used as a match pattern, it must be a def. Is
this desirable?
The keyword `abbrev` is sometimes used for an alias of a theorem, which
also results in a def. I would want to replace it with the `alias`
keyword to fix this, but it isn't available.
- dupNamespace:
I fixed some of these, but left `Tactic.Tactic` and `Parser.Parser` as
they are as these seem intended.
- unusedHaveSuffices:
I cleaned up a few proofs with unused `have` or `suffices`
- explicitVarsOfIff:
I didn't fix any of these, because that would be a breaking change.
- simpNF:
I didn't fix any of these, because I think that requires knowing the
intended simplification order.
Part of the retreat Hackathon.
---------
Co-authored-by: David Thrane Christiansen <david@davidchristiansen.dk>
Co-authored-by: Mario Carneiro <di.gama@gmail.com>
* move Measure to Nat namespace
We could (and maybe should) also move various other declarations to namespaces, like measure. However, measure seems to be used a lot in termination_by statements, so that requires other fixes as well. Measure seems to be almost unused
* fix
* delete Measure and SizeOfRef instead
