Switches from encoding `let_fun` using an annotated `(fun x : t => b) v`
expression to a function application `letFun v (fun x : t => b)`.
---------
Co-authored-by: Sebastian Ullrich <sebasti@nullri.ch>
Fixes reference implementation of `ByteArray.copySlice`, as reported
https://github.com/leanprover/lean4/issues/2966.
Adds tests.
---------
Co-authored-by: Joachim Breitner <mail@joachim-breitner.de>
This adds a `test_extern` command.
Usage:
```
import Lean.Util.TestExtern
test_extern Nat.add 17 37
```
This:
* Checks that the head symbol has an `@[extern]` attribute.
* Writes down `t == t'`, where `t` is the term provided, and `t'` is the
reference implementation (specifically, `t` with the head symbol
unfolded).
* Tries to reduce this to `true`, and complains if this fails.
Note that the type of the term must have a `BEq` instance for this to
work: there's a self-explanatory error message if it isn't available.
Fixes an issue reported on Zulip; see the test case.
* Modifies the `MonadBacktrack` instance for `SimpM` to also backtrack
the `UsedSimps` field.
* When calling the discharger, `saveState`, and then `restoreState` if
something goes wrong.
I'm not certain that it makes sense to restore the `MetaM` state if
discharging fails. I can easily change this to more conservatively just
backtrack the `UsedSimps` after failed discharging.
until around 7fe6881 the way to define well-founded recursions was to
specify a `WellFoundedRelation` on the argument explicitly. This was
rather low-level, for example one had to predict the packing of multiple
arguments into `PProd`s, the packing of mutual functions into `PSum`s,
and the cliques that were calculated.
Then the current `termination_by` syntax was introduced, where you
specify the termination argument at a higher level (one clause per
functions, unpacked arguments), and the `WellFoundedRelation` is found
using type class resolution.
The old syntax was kept around as `termination_by'`. This is not used
anywhere in the lean, std, mathlib or the theorem-proving-in-lean
repositories,
and three occurrences I found in the wild can do without
In particular, it should be possible to express anything that the old
syntax
supported also with the new one, possibly requiring a helper type with a
suitable instance, or the following generic wrapper that now lives in
std
```
def wrap {α : Sort u} {r : α → α → Prop} (h : WellFounded r) (x : α) : {x : α // Acc r x}
```
Since the old syntax is unused, has an unhelpful name and relies on
internals, this removes the support. Now is a good time before the
refactoring that's planned in #2921.
The test suite was updated without particular surprises.
The parametric `terminationHint` parser is gone, which means we can
match on syntax more easily now, in `expandDecreasingBy?`.
The elaborator is prone to duplicate terms, including recursive calls,
even if the user only wrote a single one. This duplication is wasteful
if we run the tactics on duplicated calls, and confusing in the output
of GuessLex. So prune the list of recursive calls, and remove those
where another call exists that has the same goal and context that is no
more specific.
Implements "gaps" in string literals. These are escape sequences of the
form `"\" newline whitespace+` that have the interpretation of an empty
string. For example,
```
"this is \
a string"
```
is equivalent to `"this is a string"`. These are modeled after string
continuations in
[Rust](https://doc.rust-lang.org/beta/reference/tokens.html#string-literals).
Implements RFC #2838
before code like
def dup (a : Nat) (b : Nat := a) := a + b
def rec : Nat → Nat
| 0 => 1
| n+1 => dup (dup (dup (rec n)))
decreasing_by decreasing_tactic
would run the `decreasing_tactic` 8 tims, because the recursive call
`rec n` gets duplicate due to the default paramter. Similar effects can
be observed due to dependent types or tactics like `cases`.
This is wasteful, and is confusing to the user when they use
`decreasing_by` interactively. Therfore, we now go through the proof
obligations (MVars) and if solving one would imply solving another one,
we assign the mvars to each other accordingly.
This PR is a sibling of #3004.
With
set_option showInferredTerminationBy true
this prints a message like
Inferred termination argument:
termination_by
ackermann n m => (sizeOf n, sizeOf m)
it tries hard to use names that
* match the names that the user used, if present
* have no daggers (so that it can be copied)
* do not shadow each other
* do not shadow anything from the environment (just to be nice)
it does so by appending sufficient `'` to the name.
Some of the emitted `sizeOf` calls are unnecessary, but they are needed
sometimes with dependent parameters. A follow-up PR will not emit them
for non-dependent arguments, so that in most cases the output is pretty.
Somewhen down the road we also want a code action, maybe triggered by
`termination_by?`. This should come after #2921, as that simplifies that
feature (no need to merge termination arguments from different cliques
for example.)
by showing the matrix of calls and measures, and what we know about that
call (=, <, ≤, ?), e.g.
guessLexFailures.lean:27:0-33:31: error: Could not find a decreasing
measure.
The arguments relate at each recursive call as follows:
(<, ≤, =: relation proved, ? all proofs failed, _: no proof attempted)
x1 x2 x3
1) 29:6-25 = = =
2) 30:6-23 = ? <
3) 31:6-23 < _ _
Please use `termination_by` to specify a decreasing measure
It’s a bit more verbose for mutual functions.
It will use the user-specified argument names for functions written
```
foo (n : Nat) := …
```
but not with pattern matching like
```
foo : Nat → …
| n => …
```
This can be refined later and separately (and maybe right away in
`expandMatchAltsWhereDecls`).
In order to familiarize myself with this code, and so that the next
person has an easier time, I
* added docstrings explaining what I found out these things to
* rewrote the syntax expansion functions using syntax pattern matches,
to the extend possible
If here is only one plausible measure, there is no point having the
`GuessLex` code see if it
is terminating, running all the tactics, only for the `MkFix` code then
run the tactics again.
So if there is only one plausible measure (non-mutual recursion with
only one varying
parameter), just use that measure.
Side benefit: If the function isn’t terminating, more detailed error
messages are shown
(failing proof goals), located at the recursive calls.
This improves Lean’s capabilities to guess the termination measure for
well-founded
recursion, by also trying lexicographic orders. For example:
def ackermann (n m : Nat) := match n, m with
| 0, m => m + 1
| .succ n, 0 => ackermann n 1
| .succ n, .succ m => ackermann n (ackermann (n + 1) m)
now just works.
The module docstring of `Lean.Elab.PreDefinition.WF.GuessLex` tells the
technical story.
Fixes#2837
This PR adds per-package server options to resolve#2455. It is based on
the previous work in #2456, but takes a different approach: options are
loaded for the specific file in the file worker when `print-paths` is
called, instead of loading them in the watchdog with a separate Lake
command. This change addresses review comments made in #2456.
In doing so, it introduces two new Lake config fields:
- `leanOptions`: `-D` flag options that are passed to both the language
server and `lean` when building.
- `moreServerOptions`: `-D` flag options that are passed to the language
server.
Since `print-paths` must also accept a file path to compute the options
for that file, this PR is changing the API for `print-paths`. As there
have been numerous complaints about the name `print-paths`, I also
decided to change it to `setup-file` in this PR, since it would break
compatibility with the old Lake API anyways.
This PR deprecates the Lakefile field `moreServerArgs` in favor of
`moreGlobalServerArgs`, as suggested in the review for #2456.
Fixes#2455
---------
Co-authored-by: digama0 <mcarneir@andrew.cmu.edu>
This was a Lean 3 pretty printer option. While this pretty printer
option tends to lead to confusing situations when set, it has been
frequently requested. [It is
possible](https://github.com/leanprover-community/mathlib4/pull/7910) to
implement this pretty printer option as a user, but it comes with some
artifacts -- for instance, expressions in hovers are not beta reduced.
Adding this as a core pp option is cleanest.
(We should consider having hooks into the tactic evaluator to allow
users to transform the tactic state between tactics. This would enable
beta reducing the entire local context for real, which would be useful
for teaching.)
Closes#715
The `packMutual` code ought to reliably replace all recursive calls to
the functions in `preDefs`, even when they are under- or over-applied.
Therefore eta-expand if need rsp. keep extra arguments around.
Needs a tweak to `Meta.transform` to avoid mistaking the `f` in
`f x1 x2` as a zero-arity application.
Includes a test case.
This fixes#2628 and #2883.
This didn't work before
```
def f (n : Nat) : Nat :=
match n with
| 0 => 0
| n + 1 => (f) n
```
because the `RecApp` metadata marker gets in the way. More practically
relevant, such code is to be produced when using `rw` or `simp` in
recursive theorems (see included test case).
We can fix this by preprocessing the definitions and floating the
`.mdata` marker out of applications.
For structural recursion, there already exists a `preprocess` function;
this now also floats out `.mdata` markers.
For well-founded recursion, this introduces an analogous `preprocess`
function.
Fixes#2810.
One test case output changes: With the `.mdata` out of the way, we get a
different error message. Seems fine.
Alternative approaches are:
* Leaving the `.mdata` marker where it is, and looking around it.
Tried in #2813, but not nice (many many places where `withApp` etc.
need to be adjusted).
* Moving the `.mdata` _inside_ the application, so that `withApp` still
works. Tried in #2814. Also not nice, the invariant that the `.mdata`
is around the `.const` is tedious to maintain.
the code stumbled over recursive functions whose type doesn’t have
enough manifest foralls, like:
```
def FunType := Nat → Nat
mutual
def foo : FunType
| .zero => 0
| .succ n => bar n
def bar : FunType
| .zero => 0
| .succ n => foo n
end
termination_by foo n => n; bar n => n
```
This can be fixed by using `whnf` in appropriate places, to expose the
`.forall` constructor.
Fixes#2925, comes with test case.
This implements a request handler for the `textDocument/rename` LSP
request, enabling renames via F2. It handles both local renames (e.g.
`let x := 1; x` to `let y := 1; y`) as well as global renames
(definitions).
Unfortunately it does not work for "orphan" files outside a project, as
it uses ilean data for the current file and this does not seem to be
saved for orphan files. As a result, the test file does not work,
although one can manually test the implementation against a project such
as mathlib. (This issue already exists for the "references" request,
e.g. ctrl click on the first `x` in `let x := 1; x` takes you to the
second one only if you are not in an orphan file.)
* Fixesleanprover-community/mathlib4#7124
previously, it would ignore a recursive call that has extra arguments,
which can happen when the recursive functions return something of
function type. Therefore just leave them extra arguments in place.
Fixes#2883.
previously, only the WellFounded code was making use of the error
location in the RecApp-metadata. We can do the same for structural
recursion. This way,
```
def f (n : Nat) : Nat :=
match n with
| 0 => 0
| n + 1 => f (n + 1)
```
will show the error with squiggly lines under `f (n + 1)`, and not at
`def f`.
`simp` was previously swallowing runtime exceptions and masking an
issue with this example.
`runT` is defined by well-founded recursion, but reducing the ground
term `runT x` takes a long time when `decide := true`.
Remark PR #2722 changes the `decide` default value to `false`.
When `decide := true`, we should probably have better diagnostics /
error messages for this kind of situation.
This is the same flag that the C test uses. Previously this was hidden
in the Lean compiler itself but now that the optimization pass is phased
out of the compiler we need to put it here.
Co-authored-by: Henrik Böving <hargonix@gmail.com>
