The constructor `AttributeExtensionOLeanEntry.decl` and related code
seems to be unused, and has been unused since its introduction in
a77598f7cf three years ago. Probably worth
removing (and changing the now one-constructor inductive into a
structure).
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.
Changing document string in `Attributes.lean`, in order to consistent
with code in `Lean.Parser.Attr`.
---------
Co-authored-by: Kim Morrison <kim@tqft.net>
Complement to #3967 , adds a `(since := "<date>")` field to
`@[deprecated]` so that metaprogramming code has access to the
deprecation date for e.g. bulk removals. Also adds `@[deprecated
"deprecation message"]` to optionally replace the default text
"`{declName}` has been deprecated, use `{newName}` instead".
This makes sure we can properly quote e.g. `deriving` clauses and avoids
a suspicious `eraseMacroScopes` call (though not at `Elab.Syntax`, since
categories do not have to be declaration names)
@Kha I marked the corresponding methods as `protected`.
I currently can't stand `throw_error`, and I am optimistic about
server highlighting feature you are working on :)
1) `ScopedEnvExtension` module now mananges the push/pop/activate
methods. Motivations:
- Easier to add attributes
- One `ScopedEnvExtension` may be shared between multiple
attributes (e.g., parsers)
2) Add `AttributeKind`
We need `MetaM` methods such as `isProp` to improve `ppGoal`.
This commit also moves `currNamespace` and `openDecls` to
`Core.Context`. Without this change, `Meta.ppExpr` was not taking
`open` commands into account.
@Kha I was tired of writing `arbitrary _` :)
There 0 places in the stdlib where the type needs to be provided.
If in the future we need to specify the type we can use
`arbitrary (α := <type>)`
There is no reason for having `MonadIO` anymore. The `MonadLift` type
class is well behaved in the new frontend, the `MonadFinally` solves
the problem at monad stacks such as `ExcepT e IO`.
This commit also changes the type of the IO printing functions.
For example, the type of `IO.println` was
```
def IO.println {m} [MonadIO m] {α} [ToString α] (s : α) : m Unit
```
and now it is just
```
def IO.println {α} [ToString α] (s : α) : IO Unit
```
We rely on the new frontend auto-lifting feature.
That is, if there is an instance `[MonadLiftT IO m]`, then
a term of type `IO a` is automatically coerced to `m a`
We also want a simpler `IO.println` for writing tests.
For example,
```
```
doesn't work because there isn't sufficient information for inferring
the parameter `m` in the previous `IO.println`.
The shortest workaround looked very weird
```
```
I considered adding `IO` as a default value for `m` when we have
`MonadIO m`, as we use `Nat` as the default for `ofNat a`, but it felt
like uncessary complexity.
@Kha The commit seems to work well. The auto-lifting featuring has
been working great for me. There is still room for improvement.
For example, given `MonadLiftT m n`, it doesn't automatically lift
`a -> m b` into `a -> n b`. So, code such as
`foo >>= IO.println`
had to be rewritten as
`foo >>= fun x => IO.println x`
I will add this feature later.
If you have time, please try to play with this feature and figure out
if it is stable enough for making it the default.
That is, if it roboust enough, we can stop using the following idiom
for writing functions that can be lifted automatically.
```
def instantiateLevelMVarsImp (u : Level) : MetaM Level :=
...
def instantiateLevelMVars {m} [MonadLiftT MetaM m] (u : Level) : m Level :=
liftMetaM $ instantiateLevelMVarsImp u
```
I think we only need this idiom when using `MonadControlT` which is
not as common as `MonadLiftT`.
